Yes, they're not measuring the same things.
"having trouble leaving the house" != "never leaving their room"
Re:Japan home to 541,000 young recluses
by guroot on Thursday September 08, 2016 @02:08AM
(#12450645)
You just have to phrase it correctly:
https://www.wolframalpha.com/input/?i=population+of+japan+ag...
It's 4.75% according to alpha based on a 2010 estimate.
Re:Japan home to 541,000 young recluses
by antmldr on Thursday September 08, 2016 @03:25AM
(#12450944)
I think that's the 15-19 age group...
https://www.wolframalpha.com/input/?i=population+of+japan+be...
Also, having trouble leaving the house vs: The Health, Labor and Welfare Ministry defines hikikomori as people who have stayed at home for at least six months without going to school or work, or going out to interact with others.