According to a 2014 study by Eastern Michigan University examining professional wrestlers who were active between 1985 and 2011, mortality rates for professional wrestlers are up to 2.9 times greater than the rate for men in the wider United States population. John Moriarty of the University of Manchester and Benjamin Morris of FiveThirtyEight report that the mortality rate for professional wrestlers is higher than that of athletes in other sports. Experts suggest that a combination of the physical nature of the business, no off-season, and the drug culture of the 1970s and 1980s contributes to high mortality rates among wrestlers. Another study ascribes the higher death rate largely to cardiovascular disease. Measures such as the introduction of WWE's Wellness Program have been instituted