| 年份 | 美国 |
|---|---|
| 2023 | - |
| 2022 | 1.55149 |
| 2021 | 5.77955 |
| 2020 | -3.70095 |
| 2019 | 1.82967 |
| 2018 | 2.40487 |
| 2017 | 1.59714 |
| 2016 | 0.933375 |
| 2015 | 1.953 |
| 2014 | 1.54038 |
| 2013 | 1.13869 |
| 2012 | 1.5331 |
| 2011 | 0.814519 |
| 2010 | 1.86029 |
| 2009 | -3.45002 |
| 2008 | -0.820368 |
| 2007 | 1.04493 |
| 2006 | 1.79649 |
| 2005 | 2.53378 |
| 2004 | 2.89585 |
| 2003 | 1.91648 |
| 2002 | 0.756774 |
| 2001 | -0.0399197 |
| 2000 | 2.92544 |
| 1999 | 3.59799 |
| 1998 | 3.27051 |
| 1997 | 3.19721 |
| 1996 | 2.57226 |
| 1995 | 1.46872 |
| 1994 | 2.76088 |
| 1993 | 1.40571 |
| 1992 | 2.09661 |
| 1991 | -1.4342 |
| 1990 | 0.741486 |
| 1989 | 2.69817 |
| 1988 | 3.23542 |
| 1987 | 2.53862 |
| 1986 | 2.51089 |
| 1985 | 3.25066 |
| 1984 | 6.31217 |
| 1983 | 3.63198 |
| 1982 | -2.73457 |
| 1981 | 1.53632 |
| 1980 | -1.2093 |
| 1979 | 2.03389 |
| 1978 | 4.42298 |
| 1977 | 3.57715 |
| 1976 | 4.39146 |
| 1975 | -1.18458 |
| 1974 | -1.44513 |
| 1973 | 4.64216 |
| 1972 | 4.1381 |
| 1971 | 1.9956 |
| 1970 | -1.43845 |
| 1969 | 2.09737 |
| 1968 | 3.75882 |
| 1967 | 1.38995 |
| 1966 | 5.27711 |
| 1965 | 5.0781 |
| 1964 | 4.34055 |
| 1963 | 2.90827 |
| 1962 | 4.48067 |
| 1961 | 0.618121 |
| 1960 | - |