What is the average annual income per person in the US for each year
from 1990 thru 2005?

Here's a chart that provides what I think you're looking for (thru
2004): http://www.census.gov/hhes/www/income/histinc/p01ar.html

For 2005, which only just ended less than three months ago, probably
the best you could do is finding estimates.