Source: Bureau of Labor Statistics, U.S. Department of Labor, The Economics Daily, Working alone: jobs that required little personal interaction in 2017 on the Internet at https://www.bls.gov/opub/ted/2017/working-alone-jobs-that-required-little-personal-interaction-in-2017.htm (visited December 09, 2017).
It was Gary Becker in his 1957 PhD which became The Economics of Discrimination mentioned that tiny differences in comparative advantage lead to large differences in the division of labour. He later observed that increasing returns from specialised human capital is a powerful driver of the division of labour.
Please no excuses like the recruitment pool is made up of too much of one gender and not enough of the other. The occupational choices and labour supply decisions of workers is never accepted as an excuse at the other end of this chart as valid reasons for departmental gender pay gaps.