D.C.'s ShotSpotter system detected 39,000 gunshots over the past eight years.
The Washington Post reported the system detected 9,000 incidents of gunfire in 2009 alone. That number has fallen by 40 percent.
It also shows the District averages about 17 gunshots per day since 2009.
There are at least 300 sensors across 20 square miles of the city -- about a third of the District.
The city also has some of the strictest gun control laws in the country.
