It could just be that your problem is that single-male and single-female populations have segregated themselves geographically, as in the US. Over there, the West Coast has a huge surplus of single males, the East Coast has a huge surplus of single females, and as you move towards the center of the country (where I think people are less geographically mobile, and thus less self-segregating) the surpluses disappear.
Даже карта есть на эту тему:
