Cycling emerged as the sport with the biggest doping problem over those eight years, with an average of 3.7 percent of test results coming back positive, followed by boxing (badminton had the lowest rate of the sports studied). Baseball and Basketball were next, with rates of about 2 percent. Steroids have become a common part of baseball's history. The use of performance-enhancing drugs in baseball has been widespread for many years, and while some players believe they help them recover more quickly from injury, many others believe they're essential for winning at the highest level. In fact, drug testing was not introduced until 2005, so almost all of the players who used steroids during that time would have escaped detection. According to Dr. John Stoughton, former chief medical officer for Major League Baseball, "Between 75 and 80 percent" of major league players use steroids either openly or secretly. That means that between 15 and 20 percent do not. In addition to baseball, steroid use is common in American football as well. According to author James Stewart, football players use steroids to increase their strength and speed. They do this because it is highly competitive and therefore financially rewarding to be able to play at a high level despite being much older than your peers. Steroid use is also common in basketball and hockey.