| Year | % Work force | % Private | % Public | Total members |
Private |
Public |
| 1948 | 31.8 | 34.7 | 12.1 | 14,271 | 13,591.0 | 680.9 |
| 1949 | 31.9 | 34.9 | 12.1 | 13,935 | 13,227.3 | 708.6 |
| 1950 | 31.6 | 34.6 | 12.3 | 14,294 | 13,550.4 | 743.8 |
| 1951 | 31.7 | 34.7 | 12.0 | 15,139 | 14,375.6 | 763.9 |
| 1952 | 32.0 | 35.2 | 12.0 | 15,632 | 14,839.0 | 793.0 |
| 1953 | 32.5 | 35.7 | 11.6 | 16,310 | 15,540.2 | 769.8 |
| 1954 | 32.3 | 35.6 | 11.4 | 15,808 | 15,035.9 | 772.6 |
| 1955 | 31.8 | 35.1 | 11.4 | 16,126 | 15,341.3 | 785.6 |
| 1956 | 31.4 | 34.7 | 11.1 | 16,446 | 15,641.0 | 805.0 |
| 1957 | 31.2 | 34.7 | 10.7 | 16,497 | 15,686.6 | 811.1 |
| 1958 | 30.3 | 33.9 | 10.6 | 15,570 | 14,736.0 | 834.5 |
| 1959 | 29.0 | 32.3 | 10.5 | 15,438 | 14,591.4 | 846.9 |
| 1960 | 28.6 | 31.9 | 10.8 | 15,516 | 14,613.4 | 902.7 |
| 1961 | 28.5 | 31.9 | 10.6 | 15,400 | 14,487.3 | 913.2 |
| 1962 | 30.4 | 31.6 | 24.3 | 16,893 | 14,731.9 | 2,161.9 |
| 1963 | 30.2 | 31.2 | 25.1 | 17,133 | 14,815.1 | 2,318.3 |
| 1964 | 30.2 | 31.0 | 26.0 | 17,597 | 15,101.6 | 2,495.6 |
| 1965 | 30.1 | 30.8 | 26.1 | 18,268 | 15,637.7 | 2,631.2 |
| 1966 | 29.6 | 30.3 | 26.1 | 18,922 | 16,110.8 | 2,811.2 |
| 1967 | 29.9 | 30.5 | 27.0 | 19,667 | 16,597.5 | 3,073.3 |
| 1968 | 29.5 | 29.9 | 27.3 | 20,017 | 16,782.2 | 3,235.2 |
| 1969 | 28.7 | 29.0 | 26.9 | 20,185 | 16,902.0 | 3,283.6 |
| 1970 | 29.6 | 29.1 | 32.0 | 20,990 | 16,978.3 | 4,014.0 |
| 1971 | 29.1 | 28.2 | 33.0 | 20,711 | 16,460.5 | 4,250.6 |
| 1972 | 28.8 | 27.3 | 35.4 | 21,205 | 16,484.9 | 4,720.9 |
| 1973 | 28.5 | 26.6 | 37.0 | 21,881 | 16,803.5 | 5,077.8 |
| 1974 | 28.3 | 26.2 | 38.0 | 22,165 | 16,780.8 | 5,384.6 |
| 1975 | 28.9 | 26.3 | 39.6 | 22,207 | 16,397.4 | 5,809.6 |
| 1976 | 27.9 | 25.1 | 40.2 | 22,153 | 16,172.7 | 5,980.3 |
| 1977 | 26.2 | 23.6 | 38.1 | 21,632 | 15,875.8 | 5,756.3 |
| 1978 | 25.1 | 22.5 | 36.7 | 21,756 | 16,004.5 | 5,752.0 |
| 1979 | 24.5 | 22.0 | 36.4 | 22,025 | 16,225.9 | 5,799.5 |
| 1980 | 23.2 | 20.6 | 35.1 | 20,968 | 15,273.4 | 5,694.8 |
| 1981 | 22.6 | 19.9 | 35.4 | 20,646 | 14,973.6 | 5,673.1 |
| 1982 | 21.9 | 19.0 | 35.2 | 19,571 | 14,006.9 | 5,564.5 |
| 1983 | 20.7 | 17.8 | 34.4 | 18,633 | 13,222.9 | 5,410.7 |
| 1984 | 18.8 | 15.5 | 35.8 | 17,340 | 11,647.0 | 5,654.0 |
| 1985 | 18.0 | 14.6 | 35.8 | 16,996 | 11,227.0 | 5,740.0 |
| 1986 | 17.5 | 14.0 | 36.0 | 16,975 | 11,051.0 | 5,888.0 |
| 1987 | 17.0 | 13.4 | 36.0 | 16,913 | 10,826.0 | 6,055.0 |
| 1988 | 16.8 | 12.9 | 36.7 | 17,002 | 10,674.0 | 6,298.0 |
| 1989 | 16.4 | 12.4 | 36.7 | 16,960 | 10,520.0 | 6,422.0 |
| 1990 | 16.1 | 12.1 | 36.5 | 16,740 | 10,227.0 | 6,484.0 |
| 1991 | 16.1 | 11.9 | 36.9 | 16,568 | 9,909.0 | 6,627.0 |
| 1992 | 15.8 | 11.5 | 36.7 | 16,390 | 9,703.0 | 6,650.0 |
| 1993 | 15.8 | 11.2 | 37.7 | 16,598 | 9,557 | 7,018 |
| 1994 | 15.5 | 10.9 | 38.7 | 16,748 | 9,620 | 7,094 |
| 1995 | 14.9 | 10.4 | 37.8 | 16,326 | 9,400 | 6,926 |
| 1996 | 14.5 | 10.2 | 37.6 | 16,269 | 9,385 | 6,854 |
| 1997 | 14.1 | 9.7 | 37.2 | 16,110 | 9,327 | 6,747 |
| 1998 | 13.9 | 9.5 | 37.5 | 16,211 | 9,306 | 6,905 |
| 1999 | 13.9 | 9.4 | 37.3 | 16,477 | 9,419 | 7,058 |
| 2000 | 13.5 | 9.0 | 37.5 | 16,258 | 9,148 | 7,110 |
|
2001 |
13.5 |
9.0 |
37.4 |
16,275 |
9,113 |
7,162 |
|
2002 |
13.2 |
8.5 |
37.5 |
16,107 |
8,756 |
7,351 |