The article was posted on the NCAA website December 9, 2015.
http://www.ncaa.org/about/resources/...n-s-basketball
The rate of transfer between 4-year colleges in Division I MBB is high relative to most other sports, but not the highest (M/W tennis).
The number of 4-4 transfers on Division I MBB squads has increased over the past few years (blue line in Figure 1). This is coupled with a decrease in 2-year college transfers in MBB (red line).
That said, about 40% of all MBB players who enter Division I directly out of high school depart their initial school by the end of their sophomore year.