Toasting St. Patrick’s Day with a dram of Irish whiskey? You’re not alone. Irish whiskey is one of the fastest growing spirits in the U.S., according to IWSR Drinks Analysis, a beverage market research firm. Sales volumes grew 8.6% last year, double the increase of total whiskey volumes. Irish whiskey sales are outpacing Scotch as well as U.S. and Canadian whiskeys. One reason is the proliferation of options. In 2010, there were only four distilleries in Ireland producing and selling Irish whiskey, including the longtime best-seller Jameson. Today, there are more than 30. Among them is five-year-old Teeling Distillery, which was the first distillery to open in Dublin in 125 years. U.S. consumer interest in whiskeys — and particularly in premium offerings — is also a factor, IWSR Drinks Analysis says. Increasingly, Irish distillers are releasing aged products that can command higher prices. A bottle of Redbreast 21-year Irish whiskey sells for $267.49 online. Japanese whisky is also highly sought after. IWSR says U.S. sales of Japanese whisky, from distillers like Suntory,