1950 18.6 18.1 18.5 21.1 23.9 25.0 27.0 27.5 27.1 25.1 22.4 17.9 22.7 
1951 17.4 18.2 18.4 21.9 23.3 25.9 27.1 27.5 27.5 25.7 22.0 19.8 22.9 
1952 17.6 18.4 19.8 21.3 25.1 27.1 27.6 27.9 28.3 25.5 24.1 19.9 23.6 
1953 17.5 17.6 19.3 19.7 22.7 27.7 28.5 28.2 27.4 25.0 23.3 20.9 23.2 
1954 19.0 18.0 19.2 22.3 25.4 27.0 28.5 27.8 26.9 24.2 23.0 19.6 23.4 
1955 16.7 17.8 20.7 22.4 23.9 27.1 28.2 27.8 27.7 25.1 21.5 18.9 23.2 
1956 16.8 16.3 18.9 22.0 25.8 27.5 29.1 27.8 27.4 25.8 21.9 18.3 23.1 
1957 18.3 17.6 17.4 21.5 24.0 25.4 29.0 27.7 27.4 24.1 22.3 19.0 22.8 
1958 16.8 17.5 19.1 22.3 23.8 24.9 27.3 27.9 27.1 25.6 21.9 19.9 22.8 
1959 17.1 20.3 19.7 21.1 24.3 25.9 28.1 27.6 27.8 25.1 22.9 19.6 23.3 
1960 17.1 17.3 20.1 20.3 23.2 25.7 28.5 27.7 27.5 25.8 22.5 18.9 22.9 
1961 16.6 16.7 19.3 21.0 25.2 27.7 27.8 28.2 27.5 25.5 22.7 19.4 23.1 
1962 15.8 16.5 17.8 19.9 24.9 26.7 28.5 28.1 27.5 25.5 22.9 18.5 22.7 
1963 14.5 15.1 17.7 21.3 25.3 27.0 28.2 28.2 27.8 24.3 21.3 19.2 22.5 
1964 18.7 17.8 18.6 24.0 24.5 25.8 28.4 27.7 28.1 26.0 22.0 19.6 23.4 
1965 17.0 17.6 17.1 20.4 23.3 26.5 28.7 28.1 26.5 23.5 23.1 19.5 22.6 
1966 17.9 18.4 20.4 22.2 23.0 25.1 27.4 27.7 26.6 23.8 22.5 19.5 22.9 
1967 16.4 16.8 18.3 22.3 24.2 26.5 28.5 27.9 26.8 25.0 23.5 17.4 22.8 
1968 16.5 15.3 18.2 20.0 22.2 25.5 27.7 27.7 26.8 23.9 21.9 19.8 22.1 
1969 19.7 18.7 19.1 21.1 24.4 25.3 28.0 28.4 28.0 25.2 21.3 18.5 23.1 
1970 16.2 17.4 17.8 20.6 23.6 26.5 28.1 28.0 27.0 25.9 21.9 19.0 22.7 
1971 15.7 17.1 17.4 21.2 23.4 28.3 29.2 27.4 27.4 25.2 22.2 19.4 22.8 
1972 18.4 18.2 17.9 20.4 23.9 26.0 28.1 27.7 26.3 24.3 22.6 19.8 22.8 
1973 18.0 19.1 18.9 23.4 23.8 24.9 27.2 27.0 26.9 25.3 21.2 16.6 22.7 
1974 16.5 17.1 18.0 21.5 23.6 25.5 27.4 27.7 26.1 26.4 22.6 20.6 22.8 
1975 17.3 17.9 18.4 21.5 24.0 26.1 27.2 27.4 26.8 25.8 22.1 18.5 22.8 
1976 16.0 18.4 19.0 22.2 24.2 26.4 26.2 27.6 25.8 24.2 21.5 19.4 22.6 
1977 17.5 16.5 19.4 21.7 24.9 27.3 28.0 28.3 27.3 25.3 22.6 19.8 23.2 
1978 17.1 17.0 18.0 21.2 23.9 26.1 27.8 27.1 27.3 25.9 22.6 19.7 22.8 
1979 17.7 18.3 19.2 21.8 22.4 26.0 28.8 27.9 27.3 24.7 22.1 19.5 23.0 
1980 17.2 16.6 19.4 21.7 24.4 27.0 28.5 29.0 27.8 25.1 23.1 17.6 23.1 
1981 15.8 17.0 19.2 21.8 23.4 25.8 27.6 28.1 26.6 24.2 22.0 18.4 22.5 
1982 16.1 17.6 19.7 20.1 24.4 25.3 27.8 27.1 26.1 24.1 22.9 19.2 22.5 
1983 18.1 17.2 19.0 23.3 24.6 26.9 28.5 28.4 28.4 26.1 21.4 17.7 23.3 
1984 16.3 16.8 18.1 20.5 23.0 26.7 28.6 27.9 27.5 24.8 23.1 19.3 22.7 
1985 17.2 17.8 20.4 20.4 24.2 25.6 27.5 27.3 27.1 25.8 21.1 19.1 22.8 
1986 15.9 16.1 18.2 21.5 23.8 26.2 28.9 27.8 27.5 24.6 22.6 19.7 22.7 
1987 16.7 17.3 20.3 22.3 24.7 26.4 28.7 28.6 27.7 26.0 23.7 19.0 23.5 
1988 19.1 18.5 20.7 20.7 23.6 26.6 29.1 28.0 27.4 25.4 20.7 18.4 23.2 
1989 18.7 18.2 18.6 21.9 23.9 26.2 28.0 28.0 27.5 25.2 22.2 18.8 23.1 
1990 17.8 19.0 19.0 20.5 23.3 26.5 29.0 28.3 27.3 25.2 23.5 19.8 23.3 
1991 18.6 17.1 20.8 22.5 23.7 28.3 29.7 29.0 28.4 25.3 22.4 19.7 23.8 
1992 17.9 17.1 21.6 21.7 22.8 25.9 27.9 27.6 27.3 25.1 22.3 19.5 23.1 
1993 18.6 17.3 18.7 20.9 24.8 26.5 28.8 28.0 27.6 25.4 23.3 19.8 23.3 
1994 18.1 17.8 17.7 22.1 23.2 26.8 29.0 28.5 26.6 24.9 23.1 21.1 23.2 
1995 17.8 17.0 18.1 22.1 23.6 26.9 28.7 28.9 28.5 26.6 21.4 18.1 23.1 
1996 17.8 17.2 19.9 19.7 22.1 26.2 28.7 26.7 27.4 24.7 23.3 18.3 22.7 
1997 16.9 17.8 20.3 22.1 24.0 25.7 28.0 28.0 27.4 24.7 23.0 20.2 23.2 
1998 19.4 19.5 19.9 23.7 26.7 27.5 29.0 29.5 28.8 27.0 24.0 20.9 24.7 
1999 18.3 17.9 21.7 22.0 23.7 27.5 27.8 27.9 28.4 26.2 22.9 19.3 23.6 
2000 18.7 16.9 18.8 21.0 22.6 26.6 27.2 27.4 26.3 26.2 24.7 21.0 23.1 
2001 18.4 19.1 18.5 21.6 24.1 28.1 29.1 28.7 27.8 26.0 22.3 19.1 23.6 
2002 17.3 17.3 19.3 21.7 24.5 27.0 28.2 28.2 27.0 24.8 21.8 19.5 23.1 
2003 16.3 18.2 18.4 22.1 24.8 26.5 29.0 28.8 28.1 24.6 24.0 18.9 23.3 
2004 17.3 17.7 19.2 21.6 25.4 26.7 28.4 29.1 27.3 25.4 23.2 21.3 23.6 
2005 17.7 18.7 17.8 21.7 23.9 26.3 28.9 28.9 27.7 26.5 22.9 18.0 23.3 
2006 18.6 18.6 18.8 21.5 24.8 27.1 29.2 29.0 28.0 26.2 23.3 20.5 23.8 
2007 18.4 17.8 19.4 20.6 23.4 26.8 28.9 28.5 28.1 26.7 23.0 19.7 23.4