2012-2014 data, might be something more recent out there:
Currently, there are 58 training programs in the United States listed in Gastrointestinal Endoscopy, with 50 having 1 position per year, and 8 having 2 positions per year, resulting in the availability of 68 positions in 2015. The ASGE reports that the vast majority of these positions fill each year. For the past 2 years, there were slightly >100 applicants for approximately 65 positions. The American Board of Internal Medicine’s website lists about 520 fellows per year, which means that there are advanced endoscopy training positions for 13% of GI fellow graduates.
http://www.gastrojournal.org/article/S0016-5085(15)00013-X/pdf