An insurer may invest in obligations issued, assumed, or guaranteed by the Asian Development Bank, in which bank the United States is a subscribing participant by virtue of an act of Congress approved March 16, 1966, entitled Asian Development Bank Act. The investments authorized by this Code section shall not be counted as an investment of reserves of paragraph (4) of Code Section 33-11-5 at any time in an amount greater than 5 percent of the insurer's admitted assets.