That's something they could add to the accounts info so it's one of those things you can find out but aren't reminded if you don't want to be.

Two games I have played had this, they were polar opposites so I can LOL at it or OMG it. Perpetuum where in 3 months I banked something like 6 hrs of log in and EVE Online where in 7 years I have banked more time than I do at work.