| 时间 | 值 （%） | 世界排名 |
|---|---|---|
| 2016 | 2.6 | 37 |
| 2015 | 1.93 | 115 |
| 2014 | 2.02 | 120 |
| 2013 | 1.37 | 137 |
| 2012 | 1.29 | 151 |
| 2011 | 0.9 | 160 |
| 2010 | 0.54 | 164 |
| 2009 | 1.23 | 141 |
| 2008 | 0.77 | 162 |
| 2007 | 1.95 | 153 |
| 2006 | 2.22 | 132 |
| 2005 | 1.61 | 138 |
| 2004 | 0.65 | 158 |
| 2003 | 0.59 | 155 |
| 2002 | 2.17 | 106 |
| 2001 | 1 | 129 |
| 2000 | 1.84 | 113 |
| 1999 | 1.5 | 110 |
| 1998 | 3.17 | 74 |
| 1997 | 1.48 | 110 |
| 1996 | 1.83 | 75 |
| 1995 | 1.99 | 67 |
| 1994 | 2.48 | 41 |
| 1993 | 2.28 | 34 |
| 1992 | 0.43 | 91 |
| 1991 | 1.2 | 56 |
| 1990 | 1.2 | 60 |
| 1989 | 1.32 | 46 |
| 1988 | 2.47 | 25 |
| 1987 | 0.92 | 53 |
| 1986 | 0.43 | 74 |