| 时间 | 值 （%） | 世界排名 |
|---|---|---|
| 2016 | 2 | 11 |
| 2015 | 1.86 | 13 |
| 2014 | 1.66 | 11 |
| 2013 | 1.68 | 12 |
| 2012 | 1.7 | 13 |
| 2011 | 1.72 | 11 |
| 2010 | 1.72 | 10 |
| 2009 | 1.84 | 12 |
| 2008 | 1.96 | 15 |
| 2007 | 2.09 | 14 |
| 2006 | 2.22 | 14 |
| 2005 | 2.37 | 14 |
| 2004 | 2.53 | 16 |
| 2003 | 2.7 | 17 |
| 2002 | 2.87 | 19 |
| 2001 | 3.05 | 24 |
| 2000 | 3.24 | 28 |
| 1999 | 3.46 | 31 |
| 1998 | 3.68 | 36 |
| 1997 | 3.9 | 38 |
| 1996 | 4.12 | 37 |
| 1995 | 4.35 | 44 |
| 1994 | 4.64 | 49 |
| 1993 | 4.67 | 53 |
| 1992 | 4.69 | 51 |
| 1991 | 4.7 | 52 |