| 时间 | 值 （%） | 世界排名 |
|---|---|---|
| 2016 | 27.2 | 69 |
| 2015 | 26.06 | 91 |
| 2014 | 24.99 | 97 |
| 2013 | 24.23 | 102 |
| 2012 | 23.27 | 113 |
| 2011 | 24.3 | 106 |
| 2010 | 21.7 | 121 |
| 2009 | 19.91 | 132 |
| 2008 | 21.9 | 123 |
| 2007 | 21.67 | 123 |
| 2006 | 22.08 | 123 |
| 2005 | 21.02 | 125 |
| 2004 | 22.35 | 122 |
| 2003 | 22.51 | 124 |
| 2002 | 21.06 | 129 |
| 2001 | 19.3 | 134 |
| 2000 | 19.18 | 136 |
| 1999 | 19.48 | 132 |
| 1998 | 20.09 | 130 |
| 1997 | 14.28 | 152 |
| 1996 | 14.22 | 147 |
| 1995 | 14.5 | 147 |
| 1994 | 15.14 | 126 |
| 1993 | 15.57 | 120 |
| 1992 | 16.2 | 119 |
| 1991 | 16.89 | 116 |
| 1990 | 17.65 | 110 |