| 时间 | 值 （%） | 世界排名 |
|---|---|---|
| 2015 | 9.68 | 16 |
| 2014 | 5.09 | 50 |
| 2013 | 4.64 | 66 |
| 2012 | 4.64 | 73 |
| 2011 | 7.61 | 54 |
| 2010 | 7.35 | 33 |
| 2009 | -.06 | 154 |
| 2008 | 12.9 | 41 |
| 2007 | 12.14 | 16 |
| 2006 | 12.87 | 14 |
| 2005 | 11.77 | 27 |
| 2004 | 12.48 | 20 |
| 2003 | 11.62 | 29 |
| 2002 | 5.25 | 59 |
| 2001 | 9.64 | 28 |
| 2000 | 31.15 | 10 |
| 1999 | 39.17 | 13 |
| 1998 | 7.79 | 60 |
| 1997 | 11.9 | 39 |
| 1996 | 23.51 | 31 |
| 1995 | 29.77 | 32 |