| 时间 | 值 （%） | 世界排名 |
|---|---|---|
| 2016 | 16.94 | 47 |
| 2015 | 16.84 | 84 |
| 2014 | 16.21 | 90 |
| 2013 | 16.03 | 103 |
| 2012 | 15.43 | 108 |
| 2011 | 14.6 | 115 |
| 2010 | 14.36 | 116 |
| 2009 | 13.84 | 114 |
| 2008 | 14.12 | 116 |
| 2007 | 13.7 | 124 |
| 2006 | 13.54 | 120 |
| 2005 | 12.91 | 120 |
| 2004 | 12.18 | 119 |
| 2003 | 11.58 | 119 |
| 2002 | 11.88 | 114 |
| 2001 | 11.64 | 117 |
| 2000 | 11.27 | 116 |
| 1999 | 10.18 | 116 |
| 1998 | 9.71 | 115 |
| 1997 | 9.37 | 114 |
| 1996 | 8.44 | 123 |
| 1995 | 8.07 | 122 |
| 1994 | 7.91 | 114 |
| 1993 | 7.9 | 116 |
| 1992 | 8.05 | 108 |
| 1991 | 8.05 | 105 |
| 1990 | 8.43 | 95 |
| 1989 | 8.44 | 91 |
| 1988 | 8.11 | 89 |
| 1987 | 8.27 | 90 |
| 1986 | 8.4 | 90 |