I don't think you understand the graph. This is what percentage of income comes from wages. So for every dollar that people earned as income on their tax sheet, 42% was listed as coming from wages. The other 58% comes from other sources like non-wage employer compensation, rental income, private business income, etc.
You can see the breakdown of the categories here:
https://fred.stlouisfed.org/release/tables?rid=53&eid=42185