| 时间 | 值 （%） | 世界排名 |
|---|---|---|
| 2016 | 20.74 | 5 |
| 2015 | 23.78 | 8 |
| 2014 | 24.01 | 6 |
| 2013 | 21.38 | 6 |
| 2012 | 19.45 | 11 |
| 2011 | 17.84 | 12 |
| 2010 | 23.3 | 9 |
| 2009 | 12.38 | 18 |
| 2008 | 6.35 | 70 |
| 2007 | 26.52 | 8 |
| 2006 | 24.98 | 7 |
| 2005 | 14.2 | 16 |
| 2004 | 21.36 | 5 |
| 2003 | 17.58 | 8 |
| 2002 | 6.7 | 28 |
| 2001 | 19.05 | 6 |
| 2000 | 16.19 | 7 |
| 1999 | 19.21 | 8 |
| 1998 | 8.53 | 23 |
| 1997 | 13.73 | 7 |
| 1996 | 10.04 | 9 |
| 1995 | 13.12 | 5 |
| 1994 | 11.59 | 7 |
| 1993 | 7.73 | 10 |
| 1992 | 4.23 | 18 |
| 1991 | 10.75 | 6 |
| 1990 | 15.42 | 3 |
| 1989 | 9.49 | 6 |
| 1988 | 14.42 | 2 |
| 1987 | 13.57 | 1 |
| 1986 | 9.21 | 1 |