DES MOINES, Iowa (AP) — Iowa regulators have approved a settlement on MidAmerican Energy’s plans to increase electric rates to cover rising costs. The Iowa Utilities Board says Tuesday the deal allows MidAmerican to increase annual revenue by $38.7 million, or 4 percent, in 2012. The utility temporarily raised rates in March. For 2013, the increase will raise $37.3 million, for a total two-year increase of 6.7 percent. Customers now pay about $2.33 more monthly due to the March increase, which will remain for the rest of the year. In 2013, average bills will go up another $1.30. Regulators say the increase in “reasonable” and less than what the company likely would have received in a traditional rate case. MidAmerican, a subsidiary of Berkshire Hathaway in Omaha, Neb., is Iowa’s largest utility with 770,000 customers.