MADISON, Wis. (AP) — The 20 highest-paid state employees last year worked for the Wisconsin Investment Board, which manages the investments of the Wisconsin Retirement System. All 20 made more than $300,000. Chief investment officer David C. Villa took home a state-high $834,000. The Department of Corrections paid the most of any state agency last year. The agency's 10,000 employees made a total of $474 million, with a median salary of $46,000. The investment board's 159 workers made an average of $151,000, highest in the state. The next-highest average was in prosecutors' offices, where 442 employees made an average of $71,000. The state Department of Administration paid a total of $1.6 billion in salaries last year. About 3 percent of the payments were for overtime.