There’s a paper by Toepler in Museum International from 2006 (“The Role and Changing Face of Non-market Provision of Culture in the United States”) that gives US figures for public funding versus other sources of income. Read it, it’s quite hard to summarise here, but one thing that struck me was that he reckons that 70-80% of museums (other than federal ones) are “non-profits” rather than publicly funderd. Another was an estimate that, including volunteering (a big contribution), gofts of cash or goods in kind contribute 15 times what comes from public funds.
Shouldn’t you be changing nappies or something?