Principal Financial Group Inc. on Thursday reported “a strong finish to a record-setting year” with a 13 percent increase in operating earnings for the fourth quarter and a 24 percent year-over-year increase. Net income available to common stockholders for the fourth quarter increased 16 percent to $270.4 million, or 91 cents per share, compared with $233.4 million, or 78 cents per share, for the fourth quarter of 2013. “We delivered outstanding results in 2014,” said Larry Zimpleman, chairman and CEO. “Despite the headwinds of a strengthening U.S. dollar and lower interest rates, we grew operating earnings and earnings per share by 24 percent over 2013 and delivered $18 billion of net cash flows, driving assets under management to a record $519 billion,” he saidin a release. Principal’s board also approved a quarterly dividend of 36 cents per share of common stock for the first quarter, a 6 percent increase over fourth-quarter 2014.