Just for fun, here's the chart again:
|Annual Bear Complaints||2007||2008||2009||2010|
|Monthly Bear Complaints|
I was very curious about the lower level of bear complaints in 2008, so asked El Jefe de Policia and the answer, of course, is simple once you know it.
Apparently in 2007 and 2009, the area had hard spring frosts, which killed off many of the berries that the bears like to dine on. This forced them to look further afield for food: Aspen city. 2008, though, had no such late frosts so the bears could hang tight in the mountains.
Just in case you want to know more about Aspen bears, they have their own website.