http://www.si.com/more-sports/2015/08/02/iaaf-doping-distance-running-scandal-leaked-blood-tests
The media outlets received 12,000 test results from 5,000 athletes and concluded that roughly one third of the medal winners in the highest-level distance events have recorded suspicious tests. A total of 146 Olympic and World Championships medals (including 55 gold medals) between 2001 and 2012 were won by runners who recorded suspicious tests.