Background Checks for Firearm Transfers, 2013–14 - Statistical Tables

"More than 180 million applications for firearm transfers or permits were subject to background checks since the effective date of the Brady Handgun Violence Prevention Act on February 28, 1994, through December 31, 2014. During this period, about 2.8 million applications (1.6%) were denied. In 2014, nearly 15 million applications were subject to background checks, and 193,000 (1.3%) were denied, including about 91,000 denied by the FBI and about 102,000 denied by state and local agencies..."
Background firearm checks

Background Checks for Firearm Transfers, 2006
"This web page describes background checks for firearm transfers conducted in 2006. The statistical tables below provide the number of applications checked by state points of contact and local agencies; the number of applications denied and the reasons for denial; and estimates of applications and denials conducted by each type of approval system. Data are also provided on appeals of denied applications and arrests for falsified applications. The Firearm Inquiry Statistics Program is an ongoing data collection effort focusing on the procedures and statistics related to background checks in selected states."