what I wonder...
how often do they ever have sex, if so how creative and or high physical stamina do they have? if they are active, do they have a partner who is adventurous, and or skilled, high stamina..
Are they with someone they are attracted to, or did they settle for " lowered expectations"?
The way it really comes to me is that there is a decent chance the numbers are not as accurate as they could be, I think partly there is a fair number who are not sexually active now( or ever) or have let one bad relationship be the decided general rule for all future encounters.
and some who just may be horridly dull in bed naturally and try to lick their wounds any way they can.