Google Inc.’s social network debuted at the top spot on a customer-service index of social-media websites, including Facebook Inc., which sank to a record low in the annual report. Google+, which was started in June 2011, tied information aggregator Wikipedia with a score of 78 in the social-media category on the American Customer Satisfaction Index E-Business Report, which ranks companies on a 100-point scale. Facebook, criticized for changes to its interface, had a score of 61, down from 66 last year and 64 in the 2010 report.