| 年份 | 美国 |
|---|---|
| 2023 | - |
| 2022 | - |
| 2021 | - |
| 2020 | 0.842179 |
| 2019 | 0.830638 |
| 2018 | 0.834689 |
| 2017 | 0.828802 |
| 2016 | 0.830047 |
| 2015 | 0.838683 |
| 2014 | 0.86577 |
| 2013 | 0.902431 |
| 2012 | 0.941731 |
| 2011 | 0.96549 |
| 2010 | 0.997357 |
| 2009 | 0.993786 |
| 2008 | 0.979356 |
| 2007 | 0.999976 |
| 2006 | 0.971756 |
| 2005 | 1.01681 |
| 2004 | 0.981261 |
| 2003 | 0.994048 |
| 2002 | 0.990102 |
| 2001 | 0.965146 |
| 2000 | 0.995311 |
| 1999 | 1.09295 |
| 1998 | 1.12097 |
| 1997 | 1.09071 |
| 1996 | 1.13875 |
| 1995 | 1.20286 |
| 1994 | 1.28285 |
| 1993 | 1.38096 |
| 1992 | 1.47254 |
| 1991 | 1.65266 |
| 1990 | 1.71178 |
| 1989 | - |
| 1988 | - |
| 1987 | - |
| 1986 | - |
| 1985 | - |
| 1984 | - |
| 1983 | - |
| 1982 | - |
| 1981 | - |
| 1980 | - |
| 1979 | - |
| 1978 | - |
| 1977 | - |
| 1976 | - |
| 1975 | - |
| 1974 | - |
| 1973 | - |
| 1972 | - |
| 1971 | - |
| 1970 | - |
| 1969 | - |
| 1968 | - |
| 1967 | - |
| 1966 | - |
| 1965 | - |
| 1964 | - |
| 1963 | - |
| 1962 | - |
| 1961 | - |
| 1960 | - |