Our son has had that application on Facebook for ages. He's visited 20% of the world (so not as much as you might have thought) according to what he has on that site right now, but I know he hasn't updated it since he went to England as his map still shows that as a country he'd like to visit rather than has already visited (he clearly didn't count our brief time in England last summer, which I can understand, but he should have counted his 5-day business trip there last month).
And my percentage would be around our son's as he's been to Iceland where I haven't been there, but I've been to some Caribbean islands that he's yet to visit. Other than that, we are pretty much the same. He's been to 33 of the "countries" listed on the Traveler's Century Club (so about 1/3 the way to his goal of being able to join that club) and I've been to 38 (and likely won't ever reach the goal to join that club). My father got to 65 countries, so nearly 2/3 the way there before he stopped traveling overseas. Perhaps I should just aim for breaking my father's 65 mark?