Even being in the top 20 percent of U.S. earners doesn’t mean much in the Golden State — In 2015, if your household income was $186,000, you were average. Average, that is, for the upper quintile (20 percent) of earners in the United States, making about 3.5 times the median household income. By all accounts, that should make you rich or really well-off — wealthy, even — according…