| 时间 | 值 （%） | 世界排名 |
|---|---|---|
| 2015 | 7.01 | 41 |
| 2014 | 7.79 | 32 |
| 2013 | 6.32 | 40 |
| 2012 | 9.47 | 30 |
| 2011 | 10.66 | 27 |
| 2010 | 11.34 | 25 |
| 2009 | 5.6 | 55 |
| 2008 | 9.61 | 39 |
| 2007 | 11.1 | 33 |
| 2006 | 14.84 | 25 |
| 2005 | 6.15 | 48 |
| 2004 | 9.19 | 22 |
| 2003 | 1.74 | 121 |
| 2002 | 1.66 | 114 |
| 2001 | 2.49 | 87 |
| 2000 | 0.04 | 164 |
| 1999 | -1.71 | 175 |
| 1998 | 6.46 | 33 |
| 1997 | 0.74 | 130 |
| 1996 | 0.11 | 157 |
| 1995 | 3.53 | 41 |
| 1994 | 3.7 | 29 |
| 1993 | 5.58 | 20 |
| 1992 | 6.76 | 10 |
| 1991 | 0.37 | 96 |
| 1990 | 6.87 | 9 |
| 1989 | 0.74 | 66 |
| 1988 | 2.85 | 22 |
| 1987 | 1.37 | 39 |
| 1986 | 0.62 | 57 |