Sex ratio: at birth: 1.06 male(s)/female under 15 years: 1.05 male(s)/female 15-64 years: 1.02 male(s)/female 65 years and over: 0.78 male(s)/female total population: 0.98 male(s)/female (2009 est.) https://www.cia.gov/library/publications/the-world-factbook/geos/ca.html This is surprising. Too many males being born and live ( due to modern medicine ) so this means there is a male surplus during the reproductive years. So this means many males would be single as they cannot marry a female? And then boom, thanks to males' inherent weakness, there are too many females during the later years.