OECD has the answer in their post Women make up most of the health sector workers but they are under-represented in high-skilled jobs (3/2017) along with a nice graphic.
The current overall health workforce is mostly composed of women. Nonetheless, female health workers remain underrepresented in highly skilled occupations, such as in surgery. As of 2015, just under half of all doctors are women across OECD countries on average. The variation across countries is significant: in Japan and Korea only around 20% of doctors are women, in Latvia and Estonia this proportion is over 70%.
It is worth noting that the U.S. is well below the OECD average with only 34.1% of its doctors female in 2015, although the current posted data set has the U.S. at 35.06% for 2015 (35.52% for 2016).
Time series data for OECD countries is available at the OECD.stat Health Care Resources page. Data for the U.S. dates back to 1993 (19.59%) through 2016. For this specific data set click physicians by age and gender on the left side bar. Within the chart click variable, measure, and year, to change the scope of the data in the spreadsheet. The data can be downloaded in multiple formats.