lawsuits claiming that it forced employees to work off the clock. "Several lawyers described it as the largest settlement ever for lawsuits over wage violations." Because Walmart employs part-time and relatively low paid workers, some workers may partially qualify for state welfare programs. This has led critics to claim that Walmart increases the burden on taxpayer-funded services. A 2002 survey by the state of Georgia's subsidized healthcare system, PeachCare, found that Walmart was the largest private employer of parents of children enrolled in its program; one quarter of the employees of Georgia Walmarts qualified to enroll their children in the federal subsidized healthcare system Medicaid. A 2004 study at the University of California, Berkeley charges that Walmart's low wages and benefits are insufficient, and although decreasing the burden on the social safety net to some extent, California taxpayers still pay $86 million a year to Walmart employees. On September 4, 2008, the Mexican Supreme Court of Justice ruled that Walmart de Mexico, the Mexican subsidiary of Walmart, must cease paying its employees in part with vouchers redeemable only at Walmart stores. In July 2016, some workers in China went on unofficial strike at Walmart stores in Nanchang, Jiangxi Province, Chengdu, Sichuan Province, and Harbin, Heilongjiang Province against the company's new working-hours scheduling system. The striking workers protested the system, which allowed managers to schedule an unlimited number of hours per day totalling up to 174 hours per month without overtime pay. According to Walmart, workers could either opt into the new schedule or keep their original shifts, but pointed out that the new scheduling, which Walmart claim most workers they had contacted supported, allowed employees to work more shifts if they choose. Chinese Walmart staff accused the country's only officially recognised union, the All-China Federation of Trade Unions (ACFTU), as being apathetic to their cause and unreceptive to workers' opinions. The ACFTU had previously signed an agreement with the company in 2006 that allowed Walmart to set up management-controlled unions instead. The union asked for the workers to return to their jobs. Reuters reported that by July 8, 2016, the striking workers returned to work when management agreed to consider their protests. Later it was reported that OUR Walmart provided strategic advice to the Walmart Chinese Workers Association (WCWA) prior to the strikes in China. In January 2018, Walmart announced the increase of the minimum wage for its U.S. employees