The context is labour v capital tax.
The chart shows the effective tax on capital(!) investment income. Only at the top (wealthy!) marginal tax rate in different countries. I was trying to work out why the wealthy are heavy users of tax havens. I prefer not to disclose my findings.
Anyway, the source is the OECD "Tax policy analysis" portal.
There is a lot of labor & capital taxation information, if you like to explore it, go for it:
link
