ANN ARBOR, Mich. — Publix Super Markets led all retailers in customer satisfaction ratings in 2012, according to results of the American Customer Satisfaction Index. Publix, based in Lakeland, Fla., scored 86 on the index, highest among retailers in eight channels of trade measured by ACSI. Publix’s score represented a 2.4% increase from 2011. Overall, supermarkets as a channel improved by 1.3% to 77 on the survey. Whole Foods Market and Kroger followed Publix among supermarket ranked by ACSI. In other results, Winn-Dixie improved 4% to 78, and Supervalu was up 2.7% to 76. Wal-Mart Stores was the industry’s top percentage gainer in 2012, but its 4.3% improvement brought it to 72, lowest among supermarkets ranked by ACSI. ACSI bases its results on 70,000 consumer interviews. It said customer satisfaction is predictive of both consumer spending and gross domestic product growth.