It would be interesting to see the population change in these circulation areas over the same time periods. If the population is going up while the circulation is going down, the situation is actually worse than the absolute comparisons would indicate.
What you said is true for the Arizona Republic. Primarily reporting on news in Phoenix, one of the fastest growing cities in the nation, yet its numbers are still declining. Once it was a good paper, but then Gannett took over and fired the conservative editorial board. The hacks who write for it now have driven it into the tank.