The average GS probably makes it to 11 years.
Even the GSDCA has a 13 Club (which my dog missed by 1 stinking day), which is actually for dogs that made 12 and up. (I don’t know if they dumbed it down to 12 from 13, hence the name.) I’m sure they acknowledge you’re pretty lucky to make it to 12.
To be honest, I’ not even sure 11 is what many GSDs make it to nowadays...I’d say usually 9-11 would be moreso on average, though like I said my lines average more like 12, 13. I did not know that the 13 club will accept 12 year old dogs, will have to check into that!