[masraum]

I'm no statistician, but couldn't you just create a graph with the distribution for each year as a line? Then you colud visually compare each line. You could even have excel create a best fit version of each line and compare those. Then if you wanted to estimate/test alternatives, you could create figured based on the formulas of the best fit lines.

It would be reasonable enough for govt work or handgrenades unless you're planning to write a paper and submit it for peer review, I would think.