| 时间 | 值 （%） | 世界排名 |
|---|---|---|
| 2016 | 6.74 | 21 |
| 2015 | 8.45 | 24 |
| 2014 | 8.31 | 22 |
| 2013 | 8.02 | 36 |
| 2012 | 11.47 | 12 |
| 2011 | 8.48 | 42 |
| 2010 | 8.09 | 52 |
| 2009 | 32.98 | 4 |
| 2008 | 8.29 | 35 |
| 2007 | 8.31 | 48 |
| 2006 | 7.46 | 57 |
| 2005 | 4.97 | 71 |
| 2004 | 5 | 84 |
| 2003 | 3.18 | 98 |
| 2002 | 3.4 | 88 |
| 2001 | 2.91 | 75 |
| 2000 | 1.81 | 123 |
| 1999 | 2.1 | 99 |
| 1998 | 2.32 | 95 |
| 1997 | 2.66 | 94 |
| 1996 | 1.45 | 113 |
| 1995 | -5.15 | 118 |
| 1994 | -11.01 | 124 |
| 1993 | -6.3 | 109 |
| 1992 | -18.94 | 119 |
| 1991 | 4.05 | 45 |
| 1990 | 1.59 | 71 |
| 1989 | 7.84 | 29 |
| 1988 | 0 | 87 |