The agency shall establish a housing cost index as defined in § 13-23-103 to be computed monthly or at such time or times as the agency in its discretion may require. The housing cost index shall serve to determine what percentage of the average Tennessee household’s gross monthly income is required to pay for primary fixed housing costs under then existing housing market conditions and to establish a basis for a threshold at which the financial assistance programs of this chapter will become effective. Thus, it is hereby found and declared that when primary housing costs, as defined by the housing cost index, reach or exceed twenty-five percent (25%) of an average Tennessee household’s gross monthly income, a majority of Tennessee citizens are excluded from the normal housing market; and, in light of that finding, when the housing cost index reaches or exceeds a factor of twenty-five percent (25%) and upon the approval of the board of directors, the financial assistance programs established in this chapter will become operative to aid in providing adequate housing for lower and moderate income persons and families as defined by § 13-23-103. Notwithstanding any other provision of this section, the agency may at any time approve the operation of the financial assistance programs of this chapter with the affirmative vote of nine (9) members of its board of directors.