| 时间 | 值 （%） | 世界排名 |
|---|---|---|
| 2016 | 8.63 | 74 |
| 2015 | 6.65 | 91 |
| 2014 | 4.18 | 128 |
| 2013 | 3.82 | 133 |
| 2012 | 3.37 | 132 |
| 2011 | 6.65 | 112 |
| 2010 | 3.5 | 137 |
| 2009 | 0.51 | 143 |
| 2008 | 2.72 | 150 |
| 2007 | 18.59 | 79 |
| 2006 | 15.02 | 102 |
| 2005 | 16.48 | 72 |
| 2004 | 3.37 | 148 |
| 2003 | 4.41 | 130 |
| 2002 | 8.26 | 102 |
| 2001 | 22.43 | 56 |
| 2000 | 1.92 | 138 |
| 1999 | 8.51 | 114 |
| 1998 | -.44 | 137 |
| 1997 | 1.12 | 145 |
| 1996 | 8.86 | 108 |
| 1995 | 3.09 | 138 |
| 1994 | 0.69 | 140 |
| 1993 | 4.17 | 115 |
| 1992 | 3.28 | 112 |
| 1991 | 4.15 | 102 |
| 1990 | 0.77 | 110 |
| 1989 | 10.96 | 86 |
| 1988 | 7.58 | 93 |
| 1987 | 5.96 | 93 |
| 1986 | 13.64 | 62 |