I knew it was bad, but I had not realized that the CTE numbers were so high from the article "...read the work of the Boston University C.T.E. center, which found evidence of degenerative brain disease in 99 percent of brains obtained from deceased N.F.L. players and 91 percent of college football players and 21 percent of those who played high school football."

From BU's site, here was the methodology: "For the study, the researchers began with the donated brains of 202 football players. Pathologists, knowing nothing of a patient’s history or symptoms, examined each brain for evidence of CTE. At the same time, clinicians—blinded to each brain’s pathology—used medical records and interviews with family members to collect detailed information about each patient’s medical history and symptoms. The group met for regular consensus meetings, where the pathologists and the clinicians presented their findings. They limited the study to football players, providing a somewhat homogeneous sample."

Stated another way (based on the study) 9 out of 10 college football players are going to leave with CTE.