年份 | 美国 |
---|---|
2023 | - |
2022 | 16.916 |
2021 | 17.127 |
2020 | 17.336 |
2019 | 17.541 |
2018 | 17.744 |
2017 | 17.942 |
2016 | 18.138 |
2015 | 18.329 |
2014 | 18.517 |
2013 | 18.701 |
2012 | 18.881 |
2011 | 19.056 |
2010 | 19.228 |
2009 | 19.394 |
2008 | 19.562 |
2007 | 19.731 |
2006 | 19.901 |
2005 | 20.072 |
2004 | 20.243 |
2003 | 20.417 |
2002 | 20.591 |
2001 | 20.766 |
2000 | 20.943 |
1999 | 21.258 |
1998 | 21.623 |
1997 | 21.992 |
1996 | 22.364 |
1995 | 22.743 |
1994 | 23.125 |
1993 | 23.512 |
1992 | 23.903 |
1991 | 24.299 |
1990 | 24.7 |
1989 | 24.911 |
1988 | 25.058 |
1987 | 25.207 |
1986 | 25.356 |
1985 | 25.506 |
1984 | 25.656 |
1983 | 25.806 |
1982 | 25.958 |
1981 | 26.11 |
1980 | 26.262 |
1979 | 26.308 |
1978 | 26.318 |
1977 | 26.327 |
1976 | 26.337 |
1975 | 26.347 |
1974 | 26.357 |
1973 | 26.367 |
1972 | 26.377 |
1971 | 26.387 |
1970 | 26.398 |
1969 | 26.667 |
1968 | 27.026 |
1967 | 27.388 |
1966 | 27.753 |
1965 | 28.121 |
1964 | 28.492 |
1963 | 28.866 |
1962 | 29.243 |
1961 | 29.623 |
1960 | 30.004 |