Year Age 1970 8.1 1971 8.3 1972 8.5 1973 8.6 1974 8.8 1975 9 1976 9.1 1977 9.3 1978 9.5 1979 9.6 1980 9.8 1981 9.9 1982 10.1 1983 10.2 1984 10.4 1985 10.5 1986 10.6 1987 10.7 1988 10.8 1989 10.9 1990 11 1991 11.1 1992 11.2 1993 11.3 1994 11.4 1995 11.5 1996 11.6 1997 11.6 1998 11.7 1999 11.8 2000 11.9 2001 11.9 2002 12 2003 12.1 2004 12.1 2005 12.2 2006 12.3 2007 12.3 2008 12.4 2009 12.4