| 时间 | 值 （%） | 世界排名 |
|---|---|---|
| 2016 | 3.2 | 48 |
| 2015 | 3.39 | 45 |
| 2014 | 3.57 | 42 |
| 2013 | 3.77 | 38 |
| 2012 | 3.97 | 33 |
| 2011 | 4.17 | 31 |
| 2010 | 4.39 | 27 |
| 2009 | 4.61 | 22 |
| 2008 | 4.84 | 20 |
| 2007 | 5.06 | 15 |
| 2006 | 5.29 | 13 |
| 2005 | 5.51 | 15 |
| 2004 | 5.76 | 12 |
| 2003 | 5.89 | 9 |
| 2002 | 6.04 | 6 |
| 2001 | 6.2 | 5 |
| 2000 | 3.43 | 57 |
| 1999 | 3.49 | 56 |
| 1998 | 3.54 | 55 |
| 1997 | 3.59 | 56 |
| 1996 | 3.7 | 54 |
| 1995 | 3.74 | 52 |
| 1994 | 3.78 | 52 |
| 1993 | 3.82 | 54 |
| 1992 | 5.8 | 13 |
| 1991 | 5.89 | 14 |
| 1990 | 5.99 | 15 |
| 1989 | 6.08 | 16 |
| 1988 | 6.2 | 15 |
| 1987 | 6.29 | 18 |
| 1986 | 6.4 | 21 |