​Like much of America, California's wealth is concentrated among a small group of high-income earners. The state has 16 million households, and just 61,000 of them -- 0.4 percent -- together account for one-fifth of the state's income, according to the latest tax return figures from the Franchise Tax Board.

Each of those 61,000 ​households reported ​income of more than $1 million on 2014 tax returns. The ranks ​of the million-plus earners ​grew from 45,000 in 2012.

Those high earners are most likely to live in the Bay Area. In Marin County, for instance, about 180 of every 10,000 households reported ​income of at least $1 million on 2014 returns, more than quadruple the statewide average.​

​The Sacramento region is not home to anywhere near that scale of wealth. About 9 of every 10,000 households in Sacramento County reported earnings of at least $1 million on 2014 returns, roughly one-fourth the statewide rate. Placer, El Dorado and Yolo Counties had rates two to three times as high, but still fell short of the state​wide​ average.

The fortunes of the wealthy are important in California because the state's income tax system is progressive. Though they represent 0.4 percent of the state's population​,​ those 60,000 households pay almost 35 percent of its income tax.

This map shows the number of 2014 tax returns per 10,000 households in each county reporting more than $1 million in earnings.

Source: Franchise Tax Board

Note: Data not shown for counties where fewer than 10 households earned over $1 million.