By reducing the time frame shown on the Ngram to "our lifetimes" we can get a better comparison of word frequency.
As the comment stated, this is indeed based "only" on data from books and magazines. However, we can see that the difference is significant: satisfaction
is consistently used over 10 times as often as contentment
.
Literature and spoken words aren't out-of-sync by tenfold, so I will say with 100% confidence that SATISFACTION
is used more often, in all manners of English communication, including between the major regions. (My own experience also agrees with that fact.)
Can't argue with data.

A modified Ngram, Perhaps a better example, with all your sample words. Those lines are pretty darn straight (ie., no fluctation) and that's a pretty huge gap between the 2 words in question.
If we were comparing the words content
versus happy
, the results would be very different. Content
is used 10000x more often than Happy
... but content
has multiple meanings, one used much more often during our tech age ("web site content", etc).