There is little concrete data on how many transgender people serve in the military, but a 2014 study estimated that 15,500 transgender people were serving in the U.S. military, which could make it the nation’s single largest employer of transgender Americans.

The Williams Institute, a think tank at UCLA School of Law that researches gender identity, came to that figure using a 2011 survey of 6,546 transgender Americans. Around 20 percent of that survey’s respondents said they had served in the U.S. armed forces.

Researchers from RAND used much lower numbers to estimate transgender-related health care costs, putting the total ranks of active transgender service members between 1,300 and 6,600 and concluding that only about 130 might seek gender-related surgeries. But even if the number of transgender service members is closer to the Williams Institute’s estimate, the cost for their medical care would be a negligible share of the military’s total health budget.