| 时间 | 值 （%） | 世界排名 |
|---|---|---|
| 2016 | 0.61 | 82 |
| 2015 | 0.49 | 119 |
| 2014 | -.28 | 162 |
| 2013 | 0.27 | 164 |
| 2012 | 2.77 | 120 |
| 2011 | 3.65 | 118 |
| 2010 | 1.4 | 146 |
| 2009 | -.84 | 167 |
| 2008 | 2.59 | 168 |
| 2007 | 2.81 | 127 |
| 2006 | 2.74 | 125 |
| 2005 | 2.29 | 134 |
| 2004 | 2.36 | 112 |
| 2003 | 3.28 | 88 |
| 2002 | 3.55 | 76 |
| 2001 | 4.39 | 77 |
| 2000 | 2.85 | 99 |
| 1999 | 2.3 | 99 |
| 1998 | 2.72 | 109 |
| 1997 | 2.16 | 127 |
| 1996 | 3.12 | 117 |
| 1995 | 4.12 | 117 |
| 1994 | 5.21 | 102 |
| 1993 | 6.5 | 80 |
| 1992 | 8.94 | 68 |
| 1991 | 10.93 | 64 |
| 1990 | 13.37 | 49 |
| 1989 | 12.62 | 46 |
| 1988 | 9.7 | 52 |
| 1987 | 9.34 | 50 |
| 1986 | 11.76 | 45 |