From the introduction: "The Bureau of Alcohol, Tobacco, Firearms and Explosives (ATF) National Tracing Center (NTC) is the nation's only crime gun tracing facility. As such, the NTC provides critical information that helps domestic and international law enforcement agencies solve firearms crimes, detect firearms trafficking and identify trends with respect to intrastate, interstate and international movement of crime guns. For calendar year (CY) 2009, the NTC traced over 354,000 firearms; CY 2010, over 285,000 firearms; CY 2011, over 319,000 firearms; CY 2012, over 332,000 firearms; CY 2013, over 336,000 firearms; and CY 2014, over 351 ,000 firearms. Over this time period the NTC has traced firearms for the United States and 127 countries. [...] The report relates only to firearms recovered in Central America and traced by ATF. The firearm trace results are based upon the supplied firearm identifiers on the Central America trace requests. The Central American trace data in this report is organized by the calendar year in which the respective authorities report the firearm was recovered, not the year in which the trace was initiated. For example, if El Salvadorian authorities recovered a firearm in 2014 but the trace was not initiated until 2015, the data will be organized in the year of recovery, 2014. Organization by recovery date provides valuable investigative leads as well as more specific trend data."
United States. Bureau of Alcohol, Tobacco, and Firearms: https://www.atf.gov/