Black women have become a critical source of Army and Air Force recruits, according to a recent analysis of Defense Department data that confirms what was becoming conventional wisdom among military experts.

The military enlistment rate for Black woman far exceeds that of White or Hispanic women. Black women now account for nearly a third of all females in the nation’s armed forces, a Pew Research Center study has concluded.

Since 1973, when the all-volunteer military was established, it said,  “the number of women serving on active duty has risen dramatically,” rising 42,000 to 167,000.

Overall, the female ranks of the military have gone from 2 to 14 percent of the enlisted ranks and from 4 to 16 percent of the officer corps over nearly four decades.

And 31 percent of the military’s 167,000 enlisted women are Black women, the researchers found, according to the New York Times. Black men represent about 16 percent of the military, roughly parallel to their share of the general U.S. population.

White women, by comparison, represent 53 percent of women in the military, while accounting for 78 percent of the civilian female population.

The surge happened after the end of the military draft, it said. The motivation is economic, Beth J. Asch, a senior economist and defense manpower expert at the Rand Corporation, told the Times. At a time when the military services are looking for high school graduates who want job training, good benefits and college tuition assistance, Black women are responding to the recruiting pitch.

Their most likely military branch choice: the Air Force, the study says. Least likely is the Marine Corps, where the emphasis is on combat deployment.

At the same time, though, the study found that military women, many of whom are married to military men, are more critical about the recent armed conflicts. According to the study, 63 percent of women said the Iraq war was not worth fighting, compared with 47 percent of men; 54 percent of women said the same about Afghanistan, compared with 39 percent of men.