| 年份 | 美国 |
|---|---|
| 2023 | - |
| 2022 | 1.93563 |
| 2021 | 5.94548 |
| 2020 | -2.7678 |
| 2019 | 2.29444 |
| 2018 | 2.94538 |
| 2017 | 2.24192 |
| 2016 | 1.66747 |
| 2015 | 2.70637 |
| 2014 | 2.28778 |
| 2013 | 1.84188 |
| 2012 | 2.28069 |
| 2011 | 1.54989 |
| 2010 | 2.70886 |
| 2009 | -2.59989 |
| 2008 | 0.122188 |
| 2007 | 2.01051 |
| 2006 | 2.78281 |
| 2005 | 3.48322 |
| 2004 | 3.85255 |
| 2003 | 2.79621 |
| 2002 | 1.69594 |
| 2001 | 0.954339 |
| 2000 | 4.07716 |
| 1999 | 4.7945 |
| 1998 | 4.48139 |
| 1997 | 4.44718 |
| 1996 | 3.77257 |
| 1995 | 2.68422 |
| 1994 | 4.02879 |
| 1993 | 2.75178 |
| 1992 | 3.52244 |
| 1991 | -0.108265 |
| 1990 | 1.88596 |
| 1989 | 3.67265 |
| 1988 | 4.17706 |
| 1987 | 3.45925 |
| 1986 | 3.46265 |
| 1985 | 4.16966 |
| 1984 | 7.23663 |
| 1983 | 4.58391 |
| 1982 | -1.80289 |
| 1981 | 2.53772 |
| 1980 | -0.25675 |
| 1979 | 3.16615 |
| 1978 | 5.53531 |
| 1977 | 4.62415 |
| 1976 | 5.38814 |
| 1975 | -0.205456 |
| 1974 | -0.540552 |
| 1973 | 5.64572 |
| 1972 | 5.25891 |
| 1971 | 3.29335 |
| 1970 | -0.283491 |
| 1969 | 3.1 |
| 1968 | 4.8 |
| 1967 | 2.5 |
| 1966 | 6.5 |
| 1965 | 6.4 |
| 1964 | 5.8 |
| 1963 | 4.4 |
| 1962 | 6.1 |
| 1961 | 2.3 |
| 1960 | - |