Note that this statistic is for household income and not personal income. For example in my household I know that my personal income is above the median while our household income is below the median. This is because my wife stays at home. However with other ENTP's I think it would be more common for them to not get married at all. This would give them a lower household income.
Yay for statistics, and how they don't really actually MEAN anything...
Ugh, hate statistics and graphs and such. They can be bent and twisted so many ways...
Whot's the sample size? How many of these 'households' had multiple contributors? Whot were the additional contributor's types? Was it an even 50/50 male/female split of all polled? Are they only using absolute solid evidence or is there a shadowfigure being referenced as well? Etc etc etc ad nausium.
In short, a list of numbers means nothing, especially not this particular list as it's too vague to really mean anything honestly.
That being said, certain types *WILL* be more likely to get paid more on average... some types may not have much desire for material possessions and won't often bother with a career that pays well but has no time to self or lacks creativity. Another may be prone to positions of management and, by association, will tend to get paid more as well for doing so.
There's really weird ones too like the ENTP, who tends to get paid very well, but also tends to bounce between jobs alot and makes several drastic career changes throughout their lives in most cases, so an ENTP on that list, for example, may have been not working that year at all, but the previous year they'd made more than anyone else.
So really, the statistics shown there are meaningless due to a severe lack of data, and that it's contaminated from the start due to having "household" information rather than singular. Seriously, whot is an "intj household"? Every single person in it is an INTJ? One person is? Everyone making money is? The person who took the poll is? How do we know that INTJ isn't just lazy (doubtful but never know) and happens to be married to someone who's rich?
Type does still play a factor, but that information posted there is doubtfully accurate in any way shape or form.