By TOM MURPHYUnitedHealth Group Inc. kept CEO Stephen J. Hemsley's salary stable in 2012 but bumped up his total compensation for a year in which the nation's largest health insurer grew earnings and enrollment and launched a major acquisition. The Minnetonka, Minn., insurer gave its top executive a compensation package valued at about $13.9 million last year, according to the company's proxy statement filed with the Securities and Exchange Commission. That's up 4 percent from the $13.4 million total he received last year. Hemsley, 60, received a $1.3 million annual salary in 2012, like he has the past several years. He also received $7 million in stock awards, which is the same total as 2011. But his performance-based bonus climbed 7 percent to $5.3 million, and he received $287,443 in other compensation, up from $154,804 in 2011. Other compensation included savings plan contributions and a $125,000 Hart-Scott-Rodino Antitrust Improvement Act filing fee payment UnitedHealth made on behalf of the CEO so he could maintain and increase his stock ownership in the company. A spokesman said UnitedHealth made the payment because Hemsley's holdings had approached an anti-trust threshold in the law. When determining the pay package, the compensation committee of UnitedHealth's board considered the insurer's growth and results, "all of which were achieved in a challenging economic environment," the proxy said. Hemsley had said heading into 2012 that high unemployment rates, which hurt enrollment, and a sluggish economy would challenge the insurer that year. UnitedHealth, which covers about 42 million people, saw its full-year earnings climb 7.5 percent last year to $5.53 billion, as revenue grew more than 8 percent to top $110 billion. The insurer's Medicare Advantage enrollment also grew, as the company solidified its position as the biggest provider of the privately run, subsidized versions of the government's Medicare program for the elderly and disabled people.