In 1993, after 20 years of the all volunteer military, the retirement figure reached 15% of separations, showing that while the volunteer force became more career-oriented than the conscription-era force, the great majority of volunteer force personnel did not make the military a long-term career.
The percentage of personnel staying until retirement varies greatly by branch of service, reflecting the differential premium placed on youth. The ground combat forces have placed a premium on youth and vigor, and the Marine Corps in particular discourages long-term service. The typical Marine generally leaves after completing a single enlistment contract of three to four years. The Air Force, on the other hand, invests heavily in technical training and seeks to retain personnel to increase the return on its investment. The Air Force is more career-oriented, and between 20 percent and 30 percent of separations have been retirements since the 1980s.