UnitedHealth is once again hiking the quarterly dividend it gives shareholders by more than 30 percent, with the latest increase tripling the initial value of a payout the nation's largest health insurer debuted in 2010. The insurer said Wednesday it will pay a cash dividend of 37.5 cents per share on June 25 to stockholders of record as of June 16. That's up nearly 10 cents from the Minnetonka, Minnesota, company's current payout of 28 cents per share. UnitedHealth Group Inc. became the first health insurer to offer more than a token payout to shareholders in 2010 when it started providing a quarterly dividend of 12.5 cents per share.