年份 | 美国 |
---|---|
2023 | - |
2022 | 3.45492 |
2021 | 3.45798 |
2020 | 3.69601 |
2019 | 3.43457 |
2018 | 3.32387 |
2017 | 3.32054 |
2016 | 3.42259 |
2015 | 3.48143 |
2014 | 3.69096 |
2013 | 4.03266 |
2012 | 4.46171 |
2011 | 4.82244 |
2010 | 4.90402 |
2009 | 4.87577 |
2008 | 4.4466 |
2007 | 4.07335 |
2006 | 4.04134 |
2005 | 4.08923 |
2004 | 4.01631 |
2003 | 3.82716 |
2002 | 3.44762 |
2001 | 3.12381 |
2000 | 3.11224 |
1999 | 3.08568 |
1998 | 3.20156 |
1997 | 3.40556 |
1996 | 3.55498 |
1995 | 3.86025 |
1994 | 4.21526 |
1993 | 4.60435 |
1992 | 4.97047 |
1991 | 4.88343 |
1990 | 5.60518 |
1989 | 5.87121 |
1988 | 6.07128 |
1987 | 6.42027 |
1986 | 6.62652 |
1985 | 6.45322 |
1984 | 6.23642 |
1983 | 6.32114 |
1982 | 6.81406 |
1981 | 5.64654 |
1980 | 5.15354 |
1979 | 4.95199 |
1978 | 4.94309 |
1977 | 5.15562 |
1976 | 5.19107 |
1975 | 5.62268 |
1974 | 5.95411 |
1973 | 5.89387 |
1972 | 6.51976 |
1971 | 6.94307 |
1970 | 8.03274 |
1969 | 8.63326 |
1968 | 9.26845 |
1967 | 9.4178 |
1966 | 8.4353 |
1965 | 7.58725 |
1964 | 8.05128 |
1963 | 8.83189 |
1962 | 9.33167 |
1961 | 9.15603 |
1960 | 8.99312 |