| 时间 | 值 （%） | 世界排名 |
|---|---|---|
| 2016 | 4.81 | 48 |
| 2015 | 4.3 | 42 |
| 2014 | 3.48 | 31 |
| 2013 | 3.42 | 32 |
| 2012 | 3.12 | 25 |
| 2011 | 3.21 | 23 |
| 2010 | 3.52 | 27 |
| 2009 | 3.1 | 22 |
| 2008 | 2.55 | 21 |
| 2007 | 2.49 | 19 |
| 2006 | 3.4 | 30 |
| 2005 | 4.38 | 38 |
| 2004 | 4.26 | 38 |
| 2003 | 4.22 | 38 |
| 2002 | 4.02 | 36 |
| 2001 | 3.74 | 32 |
| 2000 | 3.46 | 32 |
| 1999 | 3.25 | 27 |
| 1998 | 3.74 | 37 |
| 1997 | 4.69 | 46 |
| 1996 | 5.04 | 46 |
| 1995 | 6.31 | 66 |
| 1994 | 5.35 | 58 |
| 1993 | 5.97 | 69 |
| 1992 | 5.91 | 69 |
| 1991 | 5.41 | 60 |