California's $9 billion wine industry continues to expand, accounting for 75 percent of all wine -- both foreign and domestic -- consumed in the United States, according to Bob Smiley, dean of the Graduate School of Management at UC Davis, who studies wine industry economics. "We have found that the dramatic increase in premium wine sales over the past three years is attributed to perceived health benefits and the improved economy," says Smiley. "However, price increases, increased foreign wine imports and grape shortages should have the most negative impact on wine sales over the next three years." At a recent wine industry symposium in the Napa Valley, Smiley also offered advice, based on other industries, regarding how vintners can extend the natural product life cycle of brands and varietals.