I think its a lot more than 25%. In Sweden where I work, people are relaxed at their jobs. Coming in at 8.30 am and leaving at 4.30 pm with a full lunch break in the middle is normal. Taking a couple of coffee breaks or ping pong matches and chatting with collegues is normal. There is casual talk all day long and bosses are also leaving work early to pick up children, spend time with the family and just enjoy their lives. I think something around 35 hours is what we do around here, but getting payed for 40 of course.
The American culture honestly seems totally crazy to me. There is a massive difference in how you view yourselves over there. If you dont succeed at making some kind of a career, you feel like losers? Please step out of the matrix a little bit guys. Life is not getting some position in a company so you can work even more. Its about finding happiness.