| 时间 | 值 （%） | 世界排名 |
|---|---|---|
| 2016 | 4.4 | 89 |
| 2015 | 4.79 | 104 |
| 2014 | 5.26 | 105 |
| 2013 | 5.34 | 108 |
| 2012 | 5.27 | 108 |
| 2011 | 5.25 | 107 |
| 2010 | 4.78 | 110 |
| 2009 | 4.89 | 112 |
| 2008 | 6.95 | 98 |
| 2007 | 5.43 | 106 |
| 2006 | 7.21 | 99 |
| 2005 | 8.51 | 92 |
| 2004 | 9.83 | 89 |
| 2003 | 10.4 | 86 |
| 2002 | 10.91 | 83 |
| 2001 | 12.06 | 77 |
| 2000 | 12.58 | 76 |
| 1999 | 14.72 | 71 |
| 1998 | 15.41 | 70 |
| 1997 | 22.59 | 48 |
| 1996 | 12.88 | 83 |
| 1995 | 14.7 | 77 |
| 1994 | 13.34 | 81 |
| 1993 | 11.3 | 80 |
| 1992 | 12.94 | 77 |
| 1991 | 16.94 | 68 |
| 1990 | 17.03 | 68 |
| 1989 | 10.62 | 80 |
| 1988 | 10.92 | 79 |
| 1987 | 11.42 | 76 |
| 1986 | 13.14 | 69 |