Zions Bank publishes a monthly Small Business Index for Idaho. The index was a lousy 74.1 during December 2008, up from a revised 74.0 during November.

The index measures business conditions from the viewpoint of the Idaho small business owner or manager. That means conditions got ever-so-slightly more favorable from one month to the next, even as credit got crunched, bailouts blossomed, foreclosures flowered and stocks slid. (Sorry, I love alliteration.)

One reason: Unemployment rose. While increasing joblessness in Idaho is bad news for most of us, it does mean finding workers is becoming easier.

The index uses 1997 as its base year with the number 100.0. Since then, Idaho’s best year was 2006, when the index averaged 114.6. Zions hasn’t published an average for all of 2008 yet, but its quarterly and monthly data suggest the number will be about 75, the worst since at least 1990.

Jeff Thredgold, an economic consultant and public speaker in Clearfield, Utah, prepares the index for Zions. A year ago, Thredgold blamed “the national media’s constant negative reporting” for spreading weakness in the housing sector.