| 时间 | 值 （%） | 世界排名 |
|---|---|---|
| 2016 | 4.3 | 91 |
| 2015 | 4.31 | 108 |
| 2014 | 4.28 | 112 |
| 2013 | 3.7 | 122 |
| 2012 | 3.61 | 124 |
| 2011 | 4 | 116 |
| 2010 | 3.93 | 119 |
| 2009 | 4.06 | 121 |
| 2008 | 4.05 | 121 |
| 2007 | 4.03 | 120 |
| 2006 | 4.21 | 119 |
| 2005 | 4.52 | 117 |
| 2004 | 4.43 | 122 |
| 2003 | 4.86 | 119 |
| 2002 | 4.88 | 123 |
| 2001 | 4.84 | 122 |
| 2000 | 5.92 | 112 |
| 1999 | 6.2 | 109 |
| 1998 | 6.31 | 109 |
| 1997 | 5.98 | 111 |
| 1996 | 6 | 113 |
| 1995 | 7.79 | 106 |
| 1994 | 8.37 | 95 |
| 1993 | 9.04 | 91 |
| 1992 | 10.27 | 88 |
| 1991 | 10.26 | 87 |
| 1990 | 9.15 | 90 |
| 1989 | 9.13 | 84 |
| 1988 | 9.35 | 83 |
| 1987 | 9.91 | 81 |
| 1986 | 9.66 | 78 |