In 1997 in Illinois, there were 129,204 employees in the IT industry, with a total payroll of $5,488,016,000.

Doing the math means that the average IT salary was $42,476. Assuming an average 3% increase each year over the last six years would mean the current average IT salary is $50,718. I think if you just looked at the Chicago area it would be a lot higher.

source: U.S. Census Bureau

I predict that you will begin to see more demographic and statistical information from me here. That is a large part of GIS. The US gubmint has tons of GIS-ready information on the web, free for the downloading.