HONG KONG — As wine consumption skyrockets in the greater China region, businessmen here are setting their sights on California. In the wine-rich Napa valley, a growing number of businessmen are looking at vineyards for sale or commissioning bulk wine to bottle in China. Their goal: boost exports of U.S. wines to the booming China and Hong Kong markets. While wine consumption is still low in China compared with more mature markets such as the U.S., it's increasing dramatically. Over the past five years, China's consumption of U.S. wines has quadrupled, to 6.26 million liters in 2009, according to International Wine and Spirit Research, a U.K. consulting group.