Literacy is a fickle thing, claims America's Most Literate Cities Survey. In Pittsburgh's case, one year, you're up, another, you're down. The eighth annual survey released Monday pegged the city's 2010 literacy rating at No. 5 among 75 places with 250,000 people or more. In 2009, Pittsburgh was No. 4, a major leap from the year before, when the city languished in 12th place.