年份 | 美国 |
---|---|
2023 | - |
2022 | 17.9594 |
2021 | 18.243 |
2020 | 18.5113 |
2019 | 18.7359 |
2018 | 18.911 |
2017 | 19.0559 |
2016 | 19.1742 |
2015 | 19.2972 |
2014 | 19.4234 |
2013 | 19.537 |
2012 | 19.6422 |
2011 | 19.7438 |
2010 | 19.8669 |
2009 | 20.0068 |
2008 | 20.1357 |
2007 | 20.2652 |
2006 | 20.4195 |
2005 | 20.6109 |
2004 | 20.8156 |
2003 | 20.9924 |
2002 | 21.1399 |
2001 | 21.2853 |
2000 | 21.4254 |
1999 | 21.5255 |
1998 | 21.5897 |
1997 | 21.6484 |
1996 | 21.7203 |
1995 | 21.8025 |
1994 | 21.8609 |
1993 | 21.8586 |
1992 | 21.792 |
1991 | 21.6839 |
1990 | 21.5566 |
1989 | 21.4428 |
1988 | 21.359 |
1987 | 21.3187 |
1986 | 21.3753 |
1985 | 21.5317 |
1984 | 21.7107 |
1983 | 21.8836 |
1982 | 22.051 |
1981 | 22.2273 |
1980 | 22.4726 |
1979 | 22.8256 |
1978 | 23.2887 |
1977 | 23.8291 |
1976 | 24.4399 |
1975 | 25.1123 |
1974 | 25.784 |
1973 | 26.4552 |
1972 | 27.1327 |
1971 | 27.7493 |
1970 | 28.2838 |
1969 | 28.7856 |
1968 | 29.28 |
1967 | 29.7188 |
1966 | 30.2537 |
1965 | 30.5807 |
1964 | 30.5411 |
1963 | 30.5746 |
1962 | 30.7465 |
1961 | 30.9119 |
1960 | 30.8151 |