| 时间 | 值 （%） | 世界排名 |
|---|---|---|
| 2016 | 2.62 | 20 |
| 2015 | 2.43 | 17 |
| 2014 | 2.1 | 15 |
| 2013 | 2.93 | 21 |
| 2012 | 3.21 | 28 |
| 2011 | 3.47 | 31 |
| 2010 | 2.9 | 19 |
| 2009 | 2.5 | 17 |
| 2008 | 2.43 | 19 |
| 2007 | 2 | 13 |
| 2006 | 3 | 21 |
| 2005 | 3.08 | 21 |
| 2004 | 2.8 | 21 |
| 2003 | 3.03 | 20 |
| 2002 | 3.6 | 33 |
| 2001 | 5.1 | 54 |
| 2000 | 3.33 | 31 |
| 1999 | 3.28 | 29 |
| 1998 | 3.43 | 31 |
| 1997 | 3.47 | 33 |
| 1996 | 3.23 | 27 |
| 1995 | 3.46 | 33 |
| 1994 | 3.82 | 38 |
| 1993 | 3.91 | 40 |
| 1992 | 4.07 | 47 |
| 1991 | 3.6 | 43 |