| 时间 | 值 （%） | 世界排名 |
|---|---|---|
| 2015 | 16.76 | 85 |
| 2014 | 16.85 | 88 |
| 2013 | 14.64 | 117 |
| 2012 | 13.84 | 125 |
| 2011 | 12.29 | 135 |
| 2010 | 12.53 | 129 |
| 2009 | 13.86 | 113 |
| 2008 | 13.43 | 123 |
| 2007 | 12.71 | 132 |
| 2006 | 11.97 | 133 |
| 2005 | 10.76 | 136 |
| 2004 | 13.55 | 107 |
| 2003 | 14.01 | 101 |
| 2002 | 14.81 | 93 |
| 2001 | 15.56 | 86 |
| 2000 | 12.64 | 102 |
| 1999 | 18.53 | 61 |
| 1998 | 20.49 | 57 |
| 1997 | 22.27 | 45 |
| 1996 | 23.28 | 41 |
| 1995 | 21.98 | 45 |
| 1994 | 20 | 53 |
| 1993 | 22.17 | 46 |
| 1992 | 19.73 | 47 |
| 1991 | 20.15 | 41 |
| 1990 | 17.33 | 50 |