年份 | 美国 |
---|---|
2023 | - |
2022 | 17.1281 |
2021 | 16.6789 |
2020 | 16.2234 |
2019 | 15.7918 |
2018 | 15.3977 |
2017 | 15.0663 |
2016 | 14.6723 |
2015 | 14.3278 |
2014 | 14.1356 |
2013 | 13.8911 |
2012 | 13.5844 |
2011 | 13.2702 |
2010 | 13.0282 |
2009 | 12.8563 |
2008 | 12.6709 |
2007 | 12.5078 |
2006 | 12.4221 |
2005 | 12.3602 |
2004 | 12.3047 |
2003 | 12.2779 |
2002 | 12.2875 |
2001 | 12.2969 |
2000 | 12.3176 |
1999 | 12.3962 |
1998 | 12.4615 |
1997 | 12.514 |
1996 | 12.5504 |
1995 | 12.5436 |
1994 | 12.484 |
1993 | 12.4273 |
1992 | 12.3968 |
1991 | 12.3269 |
1990 | 12.2845 |
1989 | 12.2749 |
1988 | 12.1508 |
1987 | 11.9995 |
1986 | 11.9189 |
1985 | 11.8115 |
1984 | 11.6626 |
1983 | 11.5495 |
1982 | 11.4801 |
1981 | 11.3815 |
1980 | 11.2786 |
1979 | 11.175 |
1978 | 11.0386 |
1977 | 10.8648 |
1976 | 10.655 |
1975 | 10.4457 |
1974 | 10.2682 |
1973 | 10.1118 |
1972 | 9.97579 |
1971 | 9.87926 |
1970 | 9.80325 |
1969 | 9.73887 |
1968 | 9.71449 |
1967 | 9.65321 |
1966 | 9.57878 |
1965 | 9.55391 |
1964 | 9.51858 |
1963 | 9.45139 |
1962 | 9.37584 |
1961 | 9.31051 |
1960 | 9.23044 |