The Office of Inspector General for the Department of Justice has released an unclassified version of a report on the FBI's use of Section 215 from 2012-2014. The classified version of the report was provided to the Senate Committee on the Judiciary, Senate Select Committee on Intelligence, House Committee on the Judiciary, and House Permanent Select Committee on Intelligence in June 2016 as required under the USA FREEDOM Act, along with select members of Congressional oversight committees. The report is also available here.
A Review of the FBI s Use of Section 215 Orders for Business Records in 2012 through 2014 (PDF)
A Review of the FBI s Use of Section 215 Orders for Business Records in 2012 through 2014 (Text)
from DOJ OIG Report on Use of Section 215