As of the end of each calendar year commencing with the year ending December 31, 1980, the increase in the ratio of the Consumer Price Index to such index as of December 31, 1979, or the most recent December thirty first subsequent thereto as of which an increase in retirement allowances was granted, shall be determined, and if the increase equals or exceeds three percent, the retirement allowance of each beneficiary, other than a retired member or his spouse, in receipt of an allowance as of December 31, 1979, or the most recent December thirty first subsequent thereto as of which an increase was granted, shall be increased by four percent. Such increase shall commence the July first immediately following the December thirty first that the increase in ratio was determined. Any increase granted hereunder shall be permanent, irrespective of any subsequent decrease in the Consumer Price Index, and shall be included in determining any subsequent increase.

For purposes of this section, "Consumer Price Index" shall mean the Consumer Price Index for Urban Wage Earners and Clerical Workers (all items – United States City average), as published by the United States Department of Labor, Bureau of Labor Statistics.