Fig. 2

Pie charts showing region-level data pertaining to the studies included in the analysis. We grouped countries into 6 regions: Northern America, Latin America & Caribbean, Asia, Europe, Africa, and Oceania, based on the United Nations geoscheme system. Please see Additional file 1: Table S3 in our supplementary materials for the specific list of countries included within each region. Pie chart (A) depicts the percent of studies taking place in each of the 6 regions. Pie chart (B) depicts the percent of studies with military groups originating from each of the 6 regions. Pie chart (C) depicts the percent of studies whose first author is affiliated with each of the 6 regions. Some articles took place in multiple regions, studied military groups originating from multiple regions, and/or the first author had multiple affiliations. *Not applicable refers to articles which did not include the military among their study populations