Canada once. September 1998
Germany twice. June 1991 and July 1992-July 1993.
And the US the rest of the time.

For places like Australia/USA/Canada, it might also be meaningful to say how many states/provinces/etc you've been to.

So in that case:

USA:
New Mexico, Colorado, Kansas, Oklahoma, Texas, Arkansas, Missouri, Iowa, Indiana, Illinois, Wisconsin, Michigan (Upper and lower), Virginia, DC and Florida.

Canada: Ontario only

Germany: Every Bundesland (there are 16) EXCEPT Baden-Württenburg and the Saarland.