In determining the financial condition of a title insurer doing business under this chapter, the general investment provisions of sections 379.080 to 379.082 shall apply; except that, an investment in a title plant or plants in an amount equal to the actual cost shall be allowed as an admitted asset for title insurers. The aggregate amount of the investment shall not exceed twenty percent of surplus to policyholders, as shown on the most recent annual statement of the title insurer on file with the director.