| 时间 | 值 （%） | 世界排名 |
|---|---|---|
| 2015 | 8.74 | 161 |
| 2014 | 8.45 | 167 |
| 2013 | 9.1 | 170 |
| 2012 | 8.32 | 172 |
| 2011 | 10.45 | 170 |
| 2010 | 10.97 | 170 |
| 2009 | 9.75 | 170 |
| 2008 | 9.33 | 172 |
| 2007 | 12.19 | 168 |
| 2006 | 13.73 | 163 |
| 2005 | 16.74 | 149 |
| 2004 | 18.12 | 141 |
| 2003 | 20.9 | 135 |
| 2002 | 25.02 | 102 |
| 2001 | 20.97 | 128 |
| 2000 | 17.61 | 142 |
| 1999 | 12.15 | 158 |
| 1998 | 12.71 | 155 |
| 1997 | 8.96 | 160 |
| 1996 | 9.06 | 157 |
| 1995 | 9.43 | 157 |
| 1994 | 8.02 | 143 |
| 1993 | 8.7 | 137 |
| 1992 | 12.58 | 127 |