| 时间 | 值 （%） | 世界排名 |
|---|---|---|
| 2015 | 10.84 | 113 |
| 2014 | 9.19 | 134 |
| 2013 | 9.18 | 149 |
| 2012 | 9.11 | 150 |
| 2011 | 7.5 | 157 |
| 2010 | 7.2 | 159 |
| 2009 | 7.83 | 158 |
| 2008 | 8.11 | 153 |
| 2007 | 10.72 | 143 |
| 2006 | 8.44 | 148 |
| 2005 | 11.54 | 132 |
| 2004 | 10.92 | 125 |
| 2003 | 11.6 | 118 |
| 2002 | 11.69 | 116 |
| 2001 | 12.47 | 112 |
| 2000 | 12.49 | 105 |
| 1999 | 12.11 | 107 |
| 1998 | 10.75 | 109 |
| 1997 | 9.15 | 120 |
| 1991 | 13.19 | 68 |
| 1990 | 15 | 62 |
| 1989 | 13.23 | 66 |
| 1988 | 9.35 | 83 |
| 1987 | 11.93 | 63 |
| 1986 | 14.79 | 51 |