BERKELEY (CBS SF) – A new analysis from the University of California, Berkeley found, adjusting for inflation, low-wage workers in the Golden State are earning less than they did in 1979.

The analysis, performed by the school’s Center for Labor Research and Education, found workers in the bottom and middle of the wage distribution saw their earnings drop over the past three and a half decades. Workers in the 20th percentile saw the biggest drop between 1979 and 2014, 12 percent. Even workers who earned the median wage saw their inflation-adjusted earnings drop 5 percent.

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California workers who are high wage (in the 70th percentile or higher), saw steady increases in their paychecks, with workers in the 90th percentile earning 35 percent more between 1979 and 2014.

Researchers defined “low-wage” as someone who earned less than $13.63 an hour in 2014. Most work in retail and food service.

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The researchers also found the face of low-wage workers has changed through the decades. “We found that low-wage workers in California are older and more educated than they were 30 years ago, and yet they’ve seen stagnant and even declining wages,” visiting UC Berkeley sociology professor and senior researcher Annette Bernhardt said in a written statement.

Nearly half of low-wage workers attended some college, the researchers said.

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About a quarter of all Bay Area workers are considered low-wage. Santa Clara County has the most among Bay Area counties, at 190,000, followed by Alameda County (144,020) and San Francisco (108,281).