| 年份 | 美国 |
|---|---|
| 2023 | - |
| 2022 | - |
| 2021 | 17.2439 |
| 2020 | 17.2439 |
| 2019 | 17.2439 |
| 2018 | 17.2439 |
| 2017 | 17.2439 |
| 2016 | 17.1842 |
| 2015 | 17.1245 |
| 2014 | 17.0648 |
| 2013 | 17.0052 |
| 2012 | 16.9455 |
| 2011 | 17.0936 |
| 2010 | 17.2416 |
| 2009 | 17.3897 |
| 2008 | 17.5378 |
| 2007 | 17.6579 |
| 2006 | 17.9029 |
| 2005 | 18.148 |
| 2004 | 18.3931 |
| 2003 | 18.6349 |
| 2002 | 18.88 |
| 2001 | 19.1445 |
| 2000 | 19.141 |
| 1999 | 19.1472 |
| 1998 | 19.3015 |
| 1997 | 19.39 |
| 1996 | 19.5444 |
| 1995 | 19.8537 |
| 1994 | 19.8646 |
| 1993 | 19.9529 |
| 1992 | 20.0984 |
| 1991 | 20.2726 |
| 1990 | 20.2726 |
| 1989 | 20.2781 |
| 1988 | 20.2798 |
| 1987 | 20.2798 |
| 1986 | 20.5007 |
| 1985 | 20.5007 |
| 1984 | 20.5007 |
| 1983 | 20.5007 |
| 1982 | 20.5007 |
| 1981 | 20.6088 |
| 1980 | 20.6088 |
| 1979 | 20.6088 |
| 1978 | 20.6088 |
| 1977 | 20.3683 |
| 1976 | 20.3595 |
| 1975 | 20.3595 |
| 1974 | 20.3595 |
| 1973 | 20.4226 |
| 1972 | 20.4767 |
| 1971 | 20.5416 |
| 1970 | 20.6066 |
| 1969 | 20.6622 |
| 1968 | 19.7621 |
| 1967 | 19.051 |
| 1966 | 19.1839 |
| 1965 | 19.3253 |
| 1964 | 19.4308 |
| 1963 | 19.6064 |
| 1962 | 19.3357 |
| 1961 | 19.7217 |
| 1960 | - |