Data released by the government on Wednesday reinforces the scale of the increase in migrants seeking entry into the United States. In May nearly 133,000 migrants were apprehended at the border with Mexico, many turning themselves in to U.S. authorities to seek asylum.

That’s the highest number since July 2006. It also comes after a sharp drop in apprehensions early in President Trump’s administration (a drop that he, at the time, celebrated). In April 2017, there were fewer than 12,000 apprehensions — meaning that the total has grown by a factor of 10 in the two years since.

Why? As you may know, it’s largely a function of an increase in the number of “family units” — a group including a child younger than 18 and his parent or legal guardian — who are seeking to come to the United States. Since April 2017, there has been a 7,400 percent increase in the number of family members apprehended at the border.

More members of family units have been apprehended so far this fiscal year (beginning in October 2018) than migrants apprehended in total in fiscal year 2017.

That spike in families seeking entry largely goes hand-in-hand with the increase in migrants seeking asylum. Seeking asylum is legal, even after crossing into the country illegally. Children can be held in custody by the government for a limited period of time because of a legal agreement reached in 1997. After that point, children and their parents are generally released into the United States.

Some families are coming to the border, seeking asylum and then finding themselves legally in the United States while their asylum claims are processed — generally a multiyear proposition.

As we’ve reported before, Trump himself can take some credit for the increase in migration recently. When he first took office, migrants were wary. By 2018, though, migration increased. In March 2018, migration was up 38 percent over the year prior — an increase that only happened nine times in the preceding 208 months. Since March 2018, the year-over-year increase hasn’t been less than 75 percent — and eight times has topped 100 percent.

There has often been a surge in migration (and apprehensions) in the spring, as you may have noticed on that first graph. From December to April, the number of apprehensions consistently at least doubled from 2000 to 2014. After that point, the cycles were less prominent; in 2017, the low point in apprehensions in recent decades, apprehensions plummeted during that period.

The increase from January to May of this year, though, is higher than at any point in the past 19 years.

The number of apprehensions on the border with Mexico seen in May is not by itself a record. So far this fiscal year, though, nearly two-thirds of those apprehended at the border have been children or members of families with children — about 389,000 in total. In 2014, the Obama administration struggled with a surge in unaccompanied minors coming to the border. Over the course of that fiscal year, about 69,000 minors and 68,000 family members were apprehended, about 28 percent of all apprehensions.

Fiscal year 2019 still has four months to go.