| 时间 | 值 （%） | 世界排名 |
|---|---|---|
| 2015 | 11.23 | 19 |
| 2014 | 10.6 | 17 |
| 2013 | 5.93 | 42 |
| 2012 | 5.25 | 59 |
| 2011 | 7.51 | 43 |
| 2010 | 7.47 | 43 |
| 2009 | 6.06 | 52 |
| 2008 | 12.44 | 23 |
| 2007 | 18.46 | 18 |
| 2006 | 15.11 | 24 |
| 2005 | 7.07 | 39 |
| 2004 | 9.61 | 20 |
| 2003 | 8.39 | 22 |
| 2002 | 4.72 | 47 |
| 2001 | 3.41 | 71 |
| 2000 | 4.3 | 64 |
| 1999 | 2.94 | 83 |
| 1998 | 7.34 | 28 |
| 1997 | 6.91 | 23 |