MADISON, Wis. (AP) — The primary investment fund for most Wisconsin public employees and retirees grew more than 16 percent last year, roughly double its performance in 2016. The State of Wisconsin Investment Board reported Wednesday that based on preliminary numbers the $100 billion “Core Fund” grew 16.2 percent for the year. The five-year return is 8.6 percent. Both are above the performance benchmarks. About 622,000 state employees invest in the “Core Fund.” Payments to the roughly 198,000 retirees and beneficiaries drawing from the fund are leveled out over a five-year period to avoid large jumps in annuity payments or contribution rates. The more volatile “Variable Fund,” which is less diverse than the “Core Fund” and comprised entirely of stocks, gained 23.2 percent in 2017. Its five-year return is 13.3 percent. Annuity payment rates are set in March.