1997, 2001, 2010, 2019
1993, 2002, 2003, 2015, 2017
Full disclosure: while I've technically been to 10 countries outside the US, I've only spent more than a week in three of them (Canada, Peru, Italy).
Oddly enough, my three trips outside North America all occurred within a 10-year span. I have not been outside the US and Canada since.
**UPDATE** After a 13-year overseas hiatus, the family and I spent 6 days in Iceland in July 2022 :)