Notwithstanding any provision of law to the contrary, effective July 1, 1983, the monthly benefit of each person who either is receiving a benefit pursuant to a program established under RCW
28B.10.400 for their service as of July 1, 1978, or commenced receiving a monthly benefit as a surviving spouse or written designated beneficiary with an insurable interest in the retiree as of a date no later than December 31, 1982, shall be permanently increased by a post-retirement adjustment of $.74 per month for each year of creditable service the faculty member or employee established with the annuity or retirement income plan. Any fraction of a year of service shall be counted in the computation of the post-retirement adjustment.