We measure gender differences using the Cross-Gender Friending Ratio, the ratio of female friends in men's networks to the share of female friends in women's networks in a given place.
Men almost always have a lower share of female friends than women do, but the degree varies:

Across countries, the CGFR is strongly predictive of gender differences in labor force participation.
Within countries, we also find a strong correlation with gender attitudes in the World Values Survey, such as beliefs about women's suitability for politics.