In 1959 about 96% of the 6,850 students graduating from United States medical schools and 98.1% of 834 hospitals having approved internship programs participated in the National Intern Matching Program. The hospitals accepted 6,478 interns in this manner, and 251 students failed to secure internships through the services of the program. In 89% of the matches made, both the hospital and the students were able to obtain their first or second respective choices.
Darley W, Skarzynski A. EIGHTH NATIONAL INTERN MATCHING PROGRAM. JAMA. 1960;172(7):648–651. doi:10.1001/jama.1960.03020070006002