Female nurses may outnumber male nurses 10 to 1, but men in the profession still make more per capita, according to a report published in the Journal of the American Medical Association in March.

Male nurses working in chronic care made nearly $3,800 more per year than their female counterparts. Male nurses also earned about $7,700 more annually in outpatient settings and about $3,900 more in hospitals.

Using data from the “National Sample Survey of Registered Nurses from 1998-2008” and the American Community Survey from 2001-2013, researchers found disparity persisted without “statistically significant changes” throughout the entire time period.

Lead author Ulrike Muench, Ph.D., of the University of California-San Francisco told Kaiser Health News that the data didn’t establish a cause for pay disparity, but that it may be tied to negotiating starting salaries. 

The difference was most notable among nurse anesthetists, where males out-earned females by an average of $17,290 annually. Female nurses in senior academic positions were the only women to make more, $1,732 annually.