Take a peek at the NRMP's recently-published Results and Data: Specialty Matching Service. This information is not as granular or useful as Charting Outcomes of the Match (focused on the residency Match), but it's still helpful to see what percentage of a subspecialty goes unfilled. (Geriatrics had 77% unfilled in the most recent cycle. Gastroenterology had 1.5%.) The trends year over year are also instructive.