http://www.ncaa.org/about/resources/research/mens-basketball
Data on other professional opportunities in men’s basketball were collected by NCAA staff with the assistance of Marek Wojtera from eurobasket.com. Tracking 2016-17 international opportunities for the 2016 draft cohort, it was determined that an additional 751 former NCAA student-athletes played internationally, in the NBA D-League, or in the NBA as undrafted players (535 from Division I, 181 from Division II and 35 from Division III) after leaving college; this includes international players who attended NCAA institutions (previous versions of this document did not include these players). These numbers were combined with the NBA draftees to calculate an approximate NCAA to Total Professional opportunities figure (calculated as [44 + 751] / 4,152 = 19%).