"The table below [is comprised] of certain categories of U.S. arms, mostly guns and ammunition but also including missiles and other munitions, is composed of U.S. Census Bureau data from 1994-1998, as found on the Government Information Sharing Project on July 6, 2000. According to their website: 'The export statistics we compile and publish reflect, in general, both government and non-government exports of domestic and foreign merchandise (including non-monetary gold and silver,) from U.S. Foreign Trade Zones, the U.S. Customs districts (includes the 50 States, the District of Columbia and Puerto Rico), and the U.S. Virgin Islands to foreign countries, whether the exportation involves a commercial transaction or not. The statistics, therefore, include shipments under the Department of Defense Military Sales and Grant-Aid Programs, shipments for economic assistance under the Foreign Assistance Act and shipments under P.L. 480 (The Agricultural Trade Development and Assistance Act of 1954, as amended) and related laws. [...] The official U.S. export statistics are compiled by the Bureau of the Census from copies of Shipper's Export Declarations (SEDs), which are required to be filed with local Customs officials at the time the merchandise is exported from the country.'"
Federation of American Scientists: http://www.fas.org/