This story from about five years ago says, "In college, free-throw rates have hovered between 67 and 70 percent since 1960, never beating a record of 70.1 set in 1979. The pros have fared slightly better, usually ranging between 73 and 77 percent since 1955, with a record of 77.1 coming in 1974."
https://www.chicagotribune.com/sports/ct-xpm-2014-03-15-c... It seems that college free-throw percentages actually are at an all-time high.