| 时间 | 值 （%） | 世界排名 |
|---|---|---|
| 2016 | 7.84 | 73 |
| 2015 | 7.58 | 87 |
| 2014 | 7.24 | 92 |
| 2013 | 8.29 | 89 |
| 2012 | 7.51 | 93 |
| 2011 | 8.25 | 92 |
| 2010 | 8.27 | 91 |
| 2009 | 8.53 | 90 |
| 2008 | 8.85 | 86 |
| 2007 | 9.72 | 82 |
| 2006 | 10.14 | 83 |
| 2005 | 10.1 | 82 |
| 2004 | 10.74 | 83 |
| 2003 | 8.96 | 93 |
| 2002 | 10.09 | 85 |
| 2001 | 10.76 | 82 |
| 2000 | 10.58 | 85 |
| 1999 | 16.15 | 65 |
| 1998 | 19.44 | 54 |
| 1997 | 21.34 | 52 |
| 1996 | 25.21 | 43 |
| 1995 | 20.7 | 56 |
| 1994 | 35.85 | 25 |