Even after more than 30 years, readers are still eager to follow the stories set in the small Minnesota town of Lake Wobegon (population: about 1,200). After a four-year hiatus, Garrison Keillor lands a new bestseller with Lake Wobegon Summer 1956 . Viking has gone to press three times, bringing the in-print total to 236,500 copies. Keillor is on a 22-city tour, doing a total of 26 appearances. Average attendance at these events is about 500 people. Big media hits include Fresh Air (air date: Wednesday, Sept. 5) and Weekend Today (set to air yesterday), as well as reviews in the New York Times, the Los Angeles Times, the Washington Post and USA Today.