SAN FRANCISCO, Oct 30: San Francisco may become the latest US city to try to curb the consumption of sugary drinks with a proposed ballot measure to impose a tax on beverages seen as a culprit in rising rates of childhood obesity and diabetes. Supervisor Scott Wiener on Tuesday formally proposed asking voters in November 2014 to impose a 2-cents-per-ounce tax on soda and other drinks with added sugar sold in the famously liberal northern California city. (agencies)