Back in 2008, Congress, trying to finally get a coherent estimate of the  human trafficking victims in this country, ordered the FBI to get data from state and local law enforcement agencies on offenses and arrests.

Getting an accurate count on the beaten, traumatized victims subjected to forced sex or labor has eluded researchers for years. At times, various government agencies have estimated that there were as many as 50,000 victims a year in this country. Then, in 2004, another estimate came in at about 14,500 to 17,500, and then lowered it to 1,362, our colleague Jerry Markon wrote in a lengthy article in 2007.

Part of the problem is one of definition. Some estimates mix both human smuggling, which doesn’t involve force or coercion, and trafficking.

A bipartisan coalition has pushed Congress to spend millions of dollars to aid trafficking victims and to combat what lawmakers last month called a nearly $1o billion industry, a figure that Washington Post Fact Checker Glenn Kessler wrote June 2 earned “Four Pinocchios” — the worst rating possible, reserved only for true “whoppers.”

The FBI on April 6 put out its first report on human trafficking offenses and arrests for 2013. The numbers were from just 13 states reporting. (The bureau tells us that, since it’s a new category being reported, not that many departments supplied data. But it’s hoped that more data will be submitted in coming years.)

The 13 states were: Delaware, Indiana, Maryland, Michigan, Mississippi, Missouri, Montana, Nevada, Ohio, Oregon, South Dakota, Tennessee and Washington. A number of big states, such as Texas, California, Florida and New York, are not included.

Even so, the total number of human trafficking offenses reported for either “commercial sex acts” or “involuntary servitude” in those 13 states was 14. There were a total of four arrests.

We all know these horrific crimes are out there. They’re especially virulent overseas but are happening in this country as well. Figuring out the extent of the crimes, which, by definition, lurk deep in the shadows, is hard.

As one expert told Kessler: “The truth is that we really do not have very good data on this question.”