Here’s my second closer look.
Your graphs look solid and show a trend. I’m pretty sure if you did a statistical analysis of the “PR without prez” vs. District, the analysis would show the two populations are not the same.
The next question is common in statistical thought: the causation vs. correlation. In other words, there may be a correlation, but are the dependent variables actually creating the correlation. Or are there other forces more important? Or is it just a coincidence?
You might want to do some math, and base these graphs on total population of people living under these systems. And maybe divide the world into three categories based on per capita wealth. There’s a lot more graphs that can be constructed.
But the fewer countries in these new groupings, the less statistically reliable they are. Statistics is a funny science.
Anyways, it’s good you are doing this, and hopefully it gets people thinking about the political system vs. wealth inequality.
I would wager a TDG would be much better at distributing wealth — while still keeping the incentive of the wealthier classes to keep working.