| 时间 | 值 （%） | 世界排名 |
|---|---|---|
| 2016 | 15.21 | 27 |
| 2015 | 26.4 | 8 |
| 2014 | 18.05 | 21 |
| 2013 | 35.07 | 2 |
| 2012 | 22.94 | 17 |
| 2011 | 35.66 | 9 |
| 2010 | 33.14 | 8 |
| 2009 | 24.63 | 24 |
| 2008 | 62.64 | 2 |
| 2007 | 36.59 | 29 |
| 2006 | 16.42 | 93 |
| 2005 | 16.25 | 74 |
| 2004 | 29.7 | 26 |
| 2003 | 27.48 | 28 |
| 2002 | 22.63 | 40 |
| 2001 | 23.73 | 54 |
| 2000 | 45.53 | 17 |
| 1999 | 27.99 | 25 |
| 1998 | 67.76 | 5 |
| 1997 | 2.07 | 142 |
| 1996 | 39.96 | 19 |
| 1995 | 56.23 | 13 |
| 1994 | 36.54 | 39 |
| 1993 | 39.86 | 24 |
| 1992 | 15.79 | 68 |
| 1991 | 25.44 | 41 |
| 1990 | 11.07 | 76 |
| 1989 | 6.06 | 104 |
| 1988 | 21.55 | 49 |
| 1987 | 36.75 | 22 |
| 1986 | 27.15 | 26 |