What on earth is that graph showing? 2% of households make $150k, and another 2% make $151k, and another 2% make $150.01k, etc. It makes no sense at all. I think they meant to use a bar graph or histogram, and perhaps those circles are the boundaries between the bins. But then why are some much wider than others? Do 7% of households make between $30k and $90k? Normally with a bad graph, you can work out what they meant and it's just misleading, but this is too wrong to mean anything.

On a second look, the sharp edges of the curve appear to be $10k boundaries which with the text about $20k-$30k would mean they're the bin boundaries. But that assumes the text was written by someone who knew that and wasn't just reading off the line.