la-181948454-jpg-20141231California’s high cost of living has pushed hundreds of thousands of low- and middle-income workers to other states, federal data show. The trend points to a challenge for the state’s economy: how to attract workers of moderate means to some of the nation’s most expensive housing markets. The state overall has been losing people to other parts of the country since the 1990s. A snapshot of more recent U.S. Census migration numbers shows that nearly three-quarters of those who have left California for other states since 2007 earn less than $50,000 a year. Experts point to the state’s increasingly unaffordable real estate markets as a major driver of the trends. More than half of the nation’s 50 most expensive residential real estate markets are in California, according to Coldwell Banker’s Home Listing Report, including nine of the top 10. More