San Francisco ranked No. 1 , with an index score of 403 , partly on the basis of lifestyle and health factors such as the relatively high number of people who report exercising at a moderate intensity ( 55.6 percent , compared with an average of 48.4 percent for all 16 cities ) and eating at least five servings of fruits and vegetables per day ( 31.1 percent vs. 25.4 percent ) , and the low number of smokers ( 13.8 percent compared with 17.1 percent ) .