They’re not.

A quick google search:

In Japan, roughly 50% of young adults aged 18-29 report being virgins.

In the UK, about 46% of people aged 16-24 identify as virgins

10% of US males under 34 are virgins. (Source)

EDIT: The OP seems to be citing data from at least 15 years ago. But that’s precisely the problem: the world seems to have changed in that time. We have 3 times the number of virgins across age groups in just a few years, for instance.