EUGENE, Ore. – The headlines say youth is being served on the U.S. Olympic track and field team.

The numbers say that’s nothing new.

With the second half of Olympic track trials set to start Thursday, 35 of the 50 athletes who already have guaranteed themselves trips to Rio de Janeiro will be going to their first Olympics. That sort of turnover is pretty much the norm.

Data supplied by USA Track and Field shows an average of 53 percent turnover from year to year on the most recent world championship and Olympic teams, which award the same number of spots through the same qualifying process. When the gap is two years, the turnover rate is 60 percent.