Late Stage Anglo-American Empire

I applaud the use of graphs to educate but this one is lacking forcing the reader to assume a lot.

• what is the vertical axis? I assume it's percentage change since some arbitrary time but the title text could mislead one to think it is "rate of change"
• year against which everything is measured is not stated. I assume it's 2000.
• are the figures inflation adjusted? If not, the graph could well be underplaying the situation.
• I assume (again) that "average" here is the arithmetic mean but medium would be a much better measure of typical incomes and mortgages repayments because it is more robust to outliers. In a country with big disparities in wealth, the income of billionairees will skew the average high.