| 时间 | 值 （%） | 世界排名 |
|---|---|---|
| 2016 | 2.13 | 12 |
| 2015 | 1.8 | 11 |
| 2014 | 1.45 | 9 |
| 2013 | 1.33 | 8 |
| 2012 | 1.3 | 9 |
| 2011 | 2.7 | 17 |
| 2010 | 3.84 | 33 |
| 2009 | 4.28 | 37 |
| 2008 | 5.43 | 64 |
| 2007 | 5.54 | 65 |
| 2006 | 3.85 | 38 |
| 2005 | 2.6 | 19 |
| 2004 | 3.78 | 32 |
| 2003 | 5 | 48 |
| 2002 | 5.38 | 53 |
| 2001 | 5.59 | 59 |
| 2000 | 5.8 | 63 |
| 1999 | 3.02 | 23 |
| 1998 | 3.11 | 24 |
| 1997 | 2.32 | 16 |
| 1996 | 1.48 | 12 |
| 1995 | 2.1 | 16 |
| 1994 | 3.64 | 35 |
| 1993 | 1.55 | 11 |
| 1992 | 2.8 | 23 |
| 1991 | 4.5 | 50 |