| 时间 | 值 （%） | 世界排名 |
|---|---|---|
| 2016 | 4.74 | 96 |
| 2015 | 5.69 | 101 |
| 2014 | 6.2 | 110 |
| 2013 | 3.09 | 139 |
| 2012 | 4.52 | 125 |
| 2011 | 6.44 | 114 |
| 2010 | 4.2 | 134 |
| 2009 | 7.01 | 107 |
| 2008 | 13.31 | 92 |
| 2007 | 17.55 | 85 |
| 2006 | 18.09 | 81 |
| 2005 | 14.06 | 88 |
| 2004 | 8.35 | 118 |
| 2003 | 7.87 | 114 |
| 2002 | 10.32 | 91 |
| 2001 | 18.11 | 68 |
| 2000 | 8.44 | 112 |
| 1999 | 10.24 | 103 |
| 1998 | 6.04 | 108 |
| 1997 | 16.19 | 82 |
| 1996 | 6.58 | 123 |
| 1995 | 7.04 | 116 |
| 1994 | 10.18 | 106 |
| 1993 | 7.94 | 94 |
| 1992 | 9.26 | 88 |
| 1991 | 16.8 | 67 |
| 1990 | 21.48 | 43 |
| 1989 | 12.23 | 83 |
| 1988 | 15.21 | 69 |
| 1987 | 9.92 | 83 |
| 1986 | 16.9 | 54 |