| 时间 | 值 （%） | 世界排名 |
|---|---|---|
| 2016 | 0.86 | 75 |
| 2015 | 0.9 | 108 |
| 2014 | 1.61 | 108 |
| 2013 | 2 | 110 |
| 2012 | 2.49 | 132 |
| 2011 | 3.27 | 137 |
| 2010 | 1.81 | 131 |
| 2009 | 0.51 | 141 |
| 2008 | 3.22 | 165 |
| 2007 | 2.17 | 147 |
| 2006 | 1.45 | 165 |
| 2005 | 2.3 | 133 |
| 2004 | 2.06 | 126 |
| 2003 | 1.36 | 132 |
| 2002 | 1.8 | 128 |
| 2001 | 2.66 | 115 |
| 2000 | 2.4 | 109 |
| 1999 | 0.56 | 135 |
| 1998 | 0.92 | 141 |
| 1997 | 1.31 | 145 |
| 1996 | 1.84 | 140 |
| 1995 | 2.25 | 135 |
| 1994 | 2.96 | 119 |
| 1993 | 3.63 | 103 |
| 1992 | 4.03 | 98 |
| 1991 | 3.33 | 110 |
| 1990 | 3.26 | 109 |
| 1989 | 2.56 | 111 |
| 1988 | 1.93 | 106 |
| 1987 | 1.4 | 103 |
| 1986 | 1.7 | 97 |