I love that people overlook some basic shit in surveys like this.... half of the under 40s are virgins?!!! man that's shocking.... did you know that more than 25% of the people under 40.... are 10 or under, think about the ages included in the survey before you start to imagine anime girls falling from the tree's over there begging for Senpai to notice them, considering that the age of consent there ranges from 13-18 depending on the region (damn you survey for making me google that, now I have that weird question in my google history forever lol) that means that if keeping to the age of consent and of course the law there, people will say they've not had sex before that age when surveyed because it would be a crime to suggest otherwise.
If someone handed you a survey which said had you downloaded pirated TV shows and software off the internet... would you not hesitate slightly before ticking "of fucking course I have I know what a computer is"
Survey covers a group of people that around 50% of whom wouldn't be legal to have sex, since obviously anyone who dies before the age of 18 would fall into that half but no one is going to be in the region of 18-40 without having been alive for the first 18 years, so if you look at the numbers from a realistic point of view... it means that 100% if not more of the people who could be having legal sex... are having sex.
I'm sure the 'national fertility survey' didn't ask 5 years old and this survery is obviously about those who are allowed to have sex
Not sure how you didn't think about that