Sec. 20b.
| Effective Date of Retirement | Percent of Increase |
| August 1, 1970 to July 1, 1971 | 1 |
| August 1, 1969 to July 1, 1970 | 2 |
| August 1, 1968 to July 1, 1969 | 3 |
| August 1, 1967 to July 1, 1968 | 4 |
| August 1, 1966 to July 1, 1967 | 5 |
| August 1, 1965 to July 1, 1966 | 6 |
| August 1, 1964 to July 1, 1965 | 7 |
| August 1, 1963 to July 1, 1964 | 8 |
| August 1, 1962 to July 1, 1963 | 9 |
| August 1, 1961 to July 1, 1962 | 10 |
| August 1, 1960 to July 1, 1961 | 11 |
| August 1, 1959 to July 1, 1960 | 12 |
| August 1, 1958 to July 1, 1959 | 13 |
| August 1, 1957 to July 1, 1958 | 14 |
| July 1, 1956 to July 1, 1957 | 15 |
| Any time before July 1, 1956 | 25 |
History: Add. 1971, Act 205, Eff. Mar. 30, 1972