The Historical Evolution of Three Point Shooting

I observed the other day that the average points per NBA three point attempt in 2008 exceeded the average points per possession. Then the next day I read in Bill Simmons’ The Book of Basketball about how low three point percentage was in the first few years of NBA three pointers. So I thought it might be useful to take a historical look at this question. Thus the following charts points per possession and points per three point attempt ever since the three pointer was introduced in the 1980 season:

In the early years, three point percentages were terrible and a possession ending in a three point attempt tended to be a badly below-average possession. But pretty quickly either the existing players got better at shooting from long range, or else better long range shooters got recruited into the association, and three point attempts became about average. Ever since that happened, the two indicators tend to be pretty close, though with the points per three point attempt slightly above the average points per possession.

It’s be interesting to compare the comparable figures from NCAA and different European leagues. Have all leagues converged to this same equilibrium, or are there some places where the average points per three pointer is somewhat lower than the average points per possession.