| 时间 | 值 （%） | 世界排名 |
|---|---|---|
| 2016 | 8.73 | 66 |
| 2015 | 7.24 | 90 |
| 2014 | 4.83 | 107 |
| 2013 | 4.36 | 115 |
| 2012 | 3.93 | 116 |
| 2011 | 3.38 | 124 |
| 2010 | 3.83 | 121 |
| 2009 | 4.51 | 115 |
| 2008 | 3.68 | 124 |
| 2007 | 4.33 | 117 |
| 2006 | 3.96 | 122 |
| 2005 | 4.54 | 116 |
| 2004 | 5.51 | 116 |
| 2003 | 6.28 | 111 |
| 2002 | 6.26 | 112 |
| 2001 | 5.8 | 114 |
| 2000 | 5.3 | 117 |
| 1999 | 8.36 | 94 |
| 1998 | 10.96 | 87 |
| 1997 | 9.14 | 93 |
| 1996 | 8.99 | 96 |
| 1995 | 10.45 | 92 |
| 1994 | 10.31 | 85 |
| 1993 | 11.25 | 81 |
| 1992 | 11.53 | 84 |
| 1991 | 11.32 | 84 |
| 1990 | 12.86 | 78 |
| 1989 | 12.93 | 75 |
| 1988 | 13.87 | 70 |
| 1987 | 11.94 | 75 |
| 1986 | 12.09 | 72 |