| 时间 | 值 （%） | 世界排名 |
|---|---|---|
| 2016 | 3.79 | 33 |
| 2015 | 4.35 | 51 |
| 2014 | 4.4 | 59 |
| 2013 | 1.79 | 118 |
| 2012 | 3.01 | 111 |
| 2011 | 3.34 | 132 |
| 2010 | 1.41 | 144 |
| 2009 | 0.07 | 148 |
| 2008 | 8.72 | 92 |
| 2007 | 4.41 | 104 |
| 2006 | 3.39 | 109 |
| 2005 | 3.05 | 113 |
| 2004 | 1.05 | 144 |
| 2003 | 2.81 | 96 |
| 2002 | 2.49 | 100 |
| 2001 | 3.57 | 96 |
| 2000 | 3.84 | 79 |
| 1999 | 3.34 | 81 |
| 1998 | 5.11 | 82 |
| 1997 | 6.13 | 77 |
| 1996 | 7.36 | 77 |
| 1995 | 8.23 | 91 |
| 1994 | 11.44 | 73 |
| 1993 | 12.73 | 53 |
| 1992 | 15.43 | 45 |
| 1991 | 21.78 | 37 |
| 1990 | 26.04 | 26 |
| 1989 | 17.03 | 33 |
| 1988 | 14.68 | 40 |
| 1987 | 19.88 | 27 |
| 1986 | 19.48 | 27 |