A study published in the Journal of American Medical Association (JAMA) found that between 2000–2002 and 2016–2018, the proportion of 18–24-year-old individuals who reported having had no sexual activity in the past year increased among men (but not among women).1 In another recent study, similar results were reported: American men belonging to the youngest birth cohort who entered adulthood were more likely to be sexually inactive than their Millennial counterparts at the same ages just a few years prior.
The 5% is thus having half the (penile–vaginal) sex in the world.
https://onlinelibrary.wiley.com/doi/full/10.1111/bioe.13134