Nice hint dropping you did there.... 
I wonder if the median income wouldn't be better? After all, if the problem is income inequality, the average won't tell you anything; the non-Lord average gives you a very specific information that may not paint the whole picture. In many realms, city estates could skew the average up, but could be reserved to a closed elite.
Would it be thinkable to code the Gini coefficient of a realm?
I favor medians when it comes to wealth indicators. Averages are so biased.
Case in point, GDP per capita is higher in the US than in Québec. However, if you exclude the top 1%, it becomes higher in Québec than in the US. What does this mean? The US has more filthy rich people than Québec does, but unless you are among the 1% richest of your country, you are likely to live better in Québec than in the states.
All this to say, "averages" don't represent your "average" joe is people tend to imagine him (as they are rather judging the median joe with the averages).
My rant of the day against averages.
