Well, this is surprising. For one thing, a great number of virgins will never openly admit it due to all the stigmas and slurs; even highly religious unmarried young men struggle to take pride in being virgin, so the true percentage may be higher unless virginity is cool nowadays.
I used to be extremely popular among Japanese Resident Evil 5 players back in 2009-2011. From the chat I had with Japanese friends, I was left with the impression that virginity is not common over there. One of my seemingly innocent female friends (who had sex with 7 guys by the age of 24) told me about a certain player being "pure" (virgin), how unusual it is, and that she liked pure boys! Of course she asked me to keep it a secret even though the dude was only 19 year old
I also remember watching a Japanese TV program on Youtube highlighting the rarity of female virgins by asking women outdoors how many men they slept with.
But while the percentage itself does surprise me, I'm not shocked at all that porn can keep introverts from having sex for long periods of time.