Walmart's truck fleet logs millions of miles each year, and the company planned to double the fleet's efficiency between 2005 and 2015. The truck pictured is one of 15 based at Walmart's Buckeye, Arizona, distribution center that was converted to run on biofuel from reclaimed cooking grease made during food preparation at Walmart stores. Studies of food choice, dietary quality, and health have found that Supercenters in the United States are associated with increases in obesity rates and average body mass, and that shoppers at Walmart do not follow Dietary Guidelines for Americans as well as shoppers at traditional supermarkets. In January 2011, Walmart announced a program to improve the nutritional value of its store brands over five years, reduce prices for whole foods and vegetables, and open stores in low-income areas, so-called "food deserts", where there are no supermarkets. Subsequent research is limited. Walmart may increase food access and decrease food instability, but it does not appear to increase dietary quality. On April 23, 2011, the company announced that it was testing its new "Walmart To Go" home delivery system where customers will be able to order specific items offered on their website. The initial test was in San Jose, California, and the company has not yet said whether the delivery system will be rolled out nationwide. On November 14, 2012, Walmart launched its first mail subscription service called Goodies. Customers pay a $7 monthly subscription for five to eight delivered food samples each month, so they can try new foods. The service shut down in late 2013. In August 2013, the firm announced it was in talks to acquire a majority stake in the Kenya-based supermarket chain, Naivas. In June 2014, some Walmart employees went on strike in major U.S. cities demanding higher wages. In July 2014, American actor and comedian Tracy Morgan launched a lawsuit against Walmart seeking punitive damages over a multi-car pile-up which the suit alleges was caused by the driver of one of the firm's tractor-trailers who had not slept for 24 hours. Morgan's limousine was apparently hit by the trailer, injuring him and two fellow passengers and killing a fourth, fellow comedian James McNair. Walmart settled with the McNair family for $10 million, while admitting no liability. Morgan and Walmart reached a settlement in 2015 for an undisclosed amount, though Walmart later accused its insurers of "bad faith" in refusing to pay the