The civilian market for silencers soared 37% in 2013, when the total number shot up to nearly a half a million, according to the Bureau of Alcohol, Tobacco, Firearms and Explosives registry. That's compared to 360,000 in 2012 and 285,000 in 2011.
Silencers are so popular that there's a nine-month wait to have a registration approved by the ATF, according to Ben Shim, a certified firearms instructor and gun industry analyst with CRT Capital Group in Stamford, Conn.
http://money.cnn.com/2014/04/22/news/companies/gun-silencer-sales/index.html?source=cnn_bin