| 时间 | 值 （%） | 世界排名 |
|---|---|---|
| 2016 | 21.33 | 36 |
| 2015 | 21.12 | 63 |
| 2014 | 20.49 | 68 |
| 2013 | 19.41 | 86 |
| 2012 | 18.16 | 91 |
| 2011 | 17.4 | 96 |
| 2010 | 15.53 | 103 |
| 2009 | 14.91 | 107 |
| 2008 | 15.82 | 104 |
| 2007 | 15.27 | 112 |
| 2006 | 14.19 | 113 |
| 2005 | 12.46 | 127 |
| 2004 | 12.5 | 115 |
| 2003 | 12.07 | 113 |
| 2002 | 12.54 | 108 |
| 2001 | 12.8 | 108 |
| 2000 | 13.3 | 93 |
| 1999 | 12.47 | 101 |
| 1998 | 12.97 | 96 |
| 1997 | 12.1 | 95 |
| 1996 | 11.98 | 93 |
| 1995 | 12.71 | 83 |
| 1994 | 12.46 | 83 |
| 1993 | 13.12 | 83 |
| 1992 | 9.51 | 96 |
| 1991 | 10.81 | 83 |
| 1990 | 11.56 | 75 |
| 1989 | 10.92 | 74 |
| 1988 | 10.8 | 74 |
| 1987 | 11.04 | 72 |
| 1986 | 10.35 | 72 |