| 时间 | 值 （%） | 世界排名 |
|---|---|---|
| 2016 | 17.36 | 22 |
| 2015 | 24.44 | 11 |
| 2014 | 16.14 | 27 |
| 2013 | 21.66 | 14 |
| 2012 | 14.86 | 50 |
| 2011 | 18.67 | 36 |
| 2010 | 9.59 | 103 |
| 2009 | 29.62 | 15 |
| 2008 | 38.84 | 8 |
| 2007 | 18.53 | 80 |
| 2006 | 16.99 | 88 |
| 2005 | 9.74 | 118 |
| 2004 | 13.09 | 88 |
| 2003 | 10.22 | 97 |
| 2002 | 2.66 | 138 |
| 2001 | 16.78 | 72 |
| 2000 | 18.85 | 54 |
| 1999 | 21.68 | 39 |
| 1998 | 11.18 | 81 |
| 1997 | 29.54 | 28 |
| 1996 | 12.2 | 91 |
| 1995 | 15.43 | 78 |
| 1994 | 17.98 | 79 |
| 1993 | 25.02 | 48 |
| 1992 | 20.5 | 54 |
| 1991 | 22.72 | 46 |
| 1990 | 18.74 | 55 |
| 1989 | 20.95 | 46 |
| 1988 | 22.18 | 45 |
| 1987 | 22.42 | 41 |
| 1986 | 19.34 | 46 |