A protester cries during a sit-in rally for the abducted schoolgirls, at the Unity Fountain in Abuja May 15, 2014. (REUTERS/Afolabi Sotunde)

On Friday, the Nigerian military reportedly agreed to a truce with the militant group Boko Haram. According to the announcement, more than 200 Nigerian schoolgirls who were abducted this year will be freed. According to CNN, the details of the release are expected to be negotiated next week.

In August, the militant group Boko Haram declared an "Islamic state" in northeastern Nigeria, a territory largely occupied by the fighters. Boko Haram is believed to be hiding the girls somewhere in this area.

This week marked six months since the mass kidnapping took place. Here's what has happened since.

276 abducted girls

On April 14, 276 Nigerian girls were kidnapped by Boko Haram militants from a school in Chibok, northern Nigeria, according to official figures. The mass abduction occurred at night, and it took days before the full scale of the kidnapping became clear. Shortly after the abductions, a military spokesperson claimed that most of the girls had been rescued by Nigerian soldiers, but the remarks turned out to be wrong. Whether or not the Nigerian army is suited to finding the girls has been questioned: Its reputation in the rural north is bad, and it is often accused of lacking transparency and its soldiers of committing crimes. One recent video allegedly showed Nigerian soldiers slitting prisoners' throats, according to Amnesty International.

In the weeks following the mass kidnapping, criticism of the Nigerian government and the military had quickly grown as they failed to free the girls. In May, Boko Haram leader Abubakar Shekau released a video message claiming that the girls would "remain slaves with us."

186 days in captivity

Nearly 200 days have passed since the girls were abducted, and according to estimates, more than 200 schoolgirls are still being held by Boko Haram militants.

61 escapes

Only a few dozen girls have managed to escape over the past months: The Times of London cited an example of four girls who were able to flee from their captors and walked for three weeks through the jungle. Most of the escapes, however, took place shortly after the abductions, as this graph shows. As time passed, hope faded for many parents, and reports of escapes became less frequent. "The longer they're there, the greater likelihood they become dispersed, and the more difficult they are to track down," Jennifer Cook, director of the Africa Program at the Center for Strategic and International Studies, told Time magazine this week, before the reports emerged that Boko Haram was considering freeing them. There are conflicting numbers of how many girls are still in captivity — some say 215, some say 219.

The numbers used in our graph only refer to the mass kidnapping in April. Other abductions of women and girls have occurred since.

250,000-500,000 square kilometers

Boko Haram is predominantly active in the northeast of Nigeria, where the girls were kidnapped, but its sphere of influence extends further into the west and south of the country.

Sphere of influence of Boko Haram. (The Washington Post/ Gene Thorp) Sphere of influence of Boko Haram. (Gene Thorp/The Washington Post)

The militants have conducted an increasing number of attacks over the past few months and are now believed to be active in an area which could be up to 500,000 square kilometers, or 193,000 square miles. Its core area spreads over as much as 250,000 square kilometers, roughly the size of the United Kingdom. However, Boko Haram is not in full control of most of the areas in which it is active.

5,100 Boko Haram fatalities

Fatalities from non-criminal Nigerian violence — a term that includes attacks by terror groups and communal or political actors — have risen rapidly  since 2010, and Boko Haram attacks are the main driver behind this rise. The militant group has killed at least 5,100 Nigerians this year, according to estimates of the Johns Hopkins School of Advanced International Studies. This graph shows how fatalities caused by Boko Haram went up from around zero to more than 5,000 annually within only six years.

+ 3.3 million tweets

Although the threat posed by Boko Haram had grown steadily, it took until the April abductions for the conflict to make international headlines. The burst of reporting was accompanied by a huge rise in attention to Boko Haram on social media.

Up until May 13, about 3.3 million tweets were posted, using the hashtag #BringBackOurGirls. According to the BBC, most people who used the hashtag lived in Nigeria (27 percent) and the United States  (26 percent). Still, thousands of tweets are being posted each week in an effort to raise awareness about the fate of the Nigerian schoolgirls. 

57,215 retweets

The social media campaign found prominent supporters: As of Oct. 17, more than 57,000 users had retweeted Michelle Obama's message: "Our prayers are with the missing Nigerian girls and their families. It's time to #BringBackOurGirls."

80 U.S. troops

The Obama administration deployed 80 U.S. military personnel to Chad in May. In a letter, the White House said: "These personnel will support the operation of intelligence, surveillance and reconnaissance aircraft for missions over northern Nigeria and the surrounding area," and aid in the search for the missing schoolgirls. Chad is east of Nigeria. Other countries, such as China, France and Britain, have also sent military assistance to the region.

$12 per girl

According to some reports, Boko Haram started to sell some of the kidnapped girls as brides to militants in May. The value of a girl, according to Boko Haram: $12. The Associated Press cited reports of forced mass weddings which had taken place after the abductions. In a video message, Boko Haram leader Shekau had reportedly announced: "I abducted your girls. I will sell them in the market, by Allah."

$7 million reward

A screengrab taken Oct. 2 from a video released by the Nigerian Islamist extremist group Boko Haram and obtained by AFP shows the leader of Boko Haram, Abubakar Shekau, delivering a speech. (Boko Haram via AFP)

The hunt for Boko Haram leader Shekau had started well before the mass abductions of the girls. In 2013, the U.S. State Department added Shekau to its "Rewards for Justice Program," offering up to $7 million for information that led to his capture. Those efforts have been unsuccessful. A video which was released this month showed Shekau alive and in freedom.

$150 million aid

Meanwhile, USAID — the international development agency of the United States — has devoted about $150 million to programs aimed at providing education to Nigerian children and teenagers.

The programs primarily target internally displaced children and others who are affected by the violence in Nigeria. Only 28 percent of primary-age children have ever attended school in Borno, the state in which the kidnappings took place.

The low attendance rates in an area partially under the sphere of influence of Boko Haram does not seem to be a coincidence. Boko Haram's name can be translated as "Western education is sin."

The 200 Nigerian schoolgirls kidnapped six months ago by Islamist militant group Boko Haram may soon be released following a cease-fire deal. (Reuters)