| 时间 | 值 （%） | 世界排名 |
|---|---|---|
| 2015 | 8.18 | 83 |
| 2014 | 9.28 | 80 |
| 2013 | 9.36 | 82 |
| 2012 | 8.99 | 84 |
| 2011 | 10.69 | 72 |
| 2010 | 10.23 | 76 |
| 2009 | 9.6 | 83 |
| 2008 | 10.33 | 76 |
| 2007 | 9.98 | 79 |
| 2006 | 11.44 | 72 |
| 2005 | 11.96 | 71 |
| 2004 | 13.93 | 67 |
| 2003 | 13.45 | 68 |
| 2002 | 15.05 | 62 |
| 2001 | 19.98 | 53 |
| 2000 | 19.94 | 53 |
| 1999 | 20.99 | 50 |
| 1998 | 18.42 | 59 |
| 1997 | 20.46 | 55 |
| 1996 | 21.34 | 53 |
| 1995 | 20.92 | 55 |