There is created a trust fund to be known as the separately managed public funds investment account. The account is to be separately accounted for and invested by the state treasurer. All moneys remitted for investment in separate portfolios under this chapter, except those remitted by state agencies, shall be deposited in this account. All earnings on any balances in the separately managed public funds investment account, less amounts charged by the office of the state treasurer, shall be credited to the separately managed public funds investment account.