According to the following excerpt from USA Today, how important are historic sites in attracting tourists to the state? "Atlanta was the top destination for tourists visiting Georgia in 2009, and 46 percent of Georgia travelers spent some time during their trip in Atlanta, exploring the city's attractions, including the Georgia Aquarium, the World of Coca-Cola, Centennial Olympic Park, the Martin Luther King, Jr. National Historic Park, Six Flags Over Georgia and White Water amusement parks, the Atlanta Zoo and Stone Mountain Park. Almost a quarter of 2009 visitors -- 24 percent -- visited Savannah and the Georgia coast. Historic attractions were highlights for Georgia visitors in 2009: Almost 75 percent of Georgia tourists spent some of their time at an historic area, landmark or museum."