年份 | 美国 |
---|---|
2023 | - |
2022 | 26.3865 |
2021 | 25.6291 |
2020 | 24.8576 |
2019 | 24.1198 |
2018 | 23.4395 |
2017 | 22.8701 |
2016 | 22.1792 |
2015 | 21.586 |
2014 | 21.2753 |
2013 | 20.8663 |
2012 | 20.3441 |
2011 | 19.8104 |
2010 | 19.4146 |
2009 | 19.1493 |
2008 | 18.8573 |
2007 | 18.6053 |
2006 | 18.4967 |
2005 | 18.44 |
2004 | 18.3983 |
2003 | 18.3995 |
2002 | 18.4572 |
2001 | 18.5146 |
2000 | 18.5907 |
1999 | 18.7598 |
1998 | 18.8957 |
1997 | 19.0074 |
1996 | 19.094 |
1995 | 19.1057 |
1994 | 19.0145 |
1993 | 18.9112 |
1992 | 18.837 |
1991 | 18.6802 |
1990 | 18.5681 |
1989 | 18.5192 |
1988 | 18.2746 |
1987 | 17.9951 |
1986 | 17.8678 |
1985 | 17.7198 |
1984 | 17.5044 |
1983 | 17.3502 |
1982 | 17.2713 |
1981 | 17.143 |
1980 | 17.0246 |
1979 | 16.9319 |
1978 | 16.8085 |
1977 | 16.6367 |
1976 | 16.4162 |
1975 | 16.2095 |
1974 | 16.0571 |
1973 | 15.9409 |
1972 | 15.8619 |
1971 | 15.8394 |
1970 | 15.8339 |
1969 | 15.8419 |
1968 | 15.924 |
1967 | 15.922 |
1966 | 15.9202 |
1965 | 15.959 |
1964 | 15.8801 |
1963 | 15.7592 |
1962 | 15.6583 |
1961 | 15.5753 |
1960 | 15.3957 |