| 时间 | 值 （%） | 世界排名 |
|---|---|---|
| 2016 | 17.63 | 46 |
| 2015 | 16.36 | 87 |
| 2014 | 15.66 | 96 |
| 2013 | 15.09 | 111 |
| 2012 | 14.86 | 112 |
| 2011 | 14.11 | 121 |
| 2010 | 13.86 | 120 |
| 2009 | 12.7 | 125 |
| 2008 | 12.97 | 128 |
| 2007 | 13.1 | 129 |
| 2006 | 12.35 | 131 |
| 2005 | 11.07 | 134 |
| 2004 | 11.23 | 122 |
| 2003 | 10.17 | 125 |
| 2002 | 9.71 | 129 |
| 2001 | 9.84 | 127 |
| 2000 | 11.27 | 117 |
| 1999 | 9.07 | 125 |
| 1998 | 10.03 | 114 |
| 1997 | 9.22 | 118 |
| 1996 | 10.1 | 106 |
| 1995 | 12.53 | 86 |
| 1994 | 9.53 | 103 |
| 1993 | 8.15 | 114 |
| 1992 | 9.35 | 97 |
| 1991 | 7.81 | 108 |
| 1990 | 9.17 | 90 |