Does anyone have comparable numbers for other countries?
No need to understand German: Scroll to page 14 (of PDF). For Germany about 42% of the adult children live either at their parents ("Koresidenz") or within 5km of their parents. European average is 45%.
Europe's young adults living with parents - a country by country breakdown (2011)
http://www.theguardian.com/news/datablog/2014/mar/24/young-a...