| 时间 | 值 （%） | 世界排名 |
|---|---|---|
| 2016 | 0.56 | 153 |
| 2015 | 2.73 | 102 |
| 2014 | 5.99 | 35 |
| 2013 | 4.13 | 81 |
| 2012 | 4.78 | 68 |
| 2011 | 3.42 | 107 |
| 2010 | 4.82 | 87 |
| 2009 | 4.53 | 38 |
| 2008 | 6.1 | 62 |
| 2007 | 3.41 | 144 |
| 2006 | 3.36 | 152 |
| 2005 | 3.48 | 133 |
| 2004 | 4.68 | 110 |
| 2003 | 3.95 | 104 |
| 2002 | 0.12 | 167 |
| 2001 | 4.8 | 54 |
| 2000 | 6.2 | 41 |
| 1999 | 4.41 | 65 |
| 1998 | 3.02 | 123 |
| 1997 | 5.05 | 81 |
| 1996 | 5.33 | 71 |
| 1995 | 3.47 | 108 |
| 1994 | 8.22 | 21 |
| 1993 | 3.85 | 75 |
| 1992 | 4.11 | 62 |
| 1991 | 6.37 | 32 |
| 1990 | 4.64 | 58 |
| 1989 | 4.33 | 69 |
| 1988 | 7.7 | 37 |
| 1987 | 1.7 | 113 |
| 1986 | 4.57 | 65 |