| 时间 | 值 （%） | 世界排名 |
|---|---|---|
| 2016 | 2.2 | 116 |
| 2015 | 2.29 | 135 |
| 2014 | 2.33 | 137 |
| 2013 | 2.34 | 139 |
| 2012 | 2.46 | 135 |
| 2011 | 2.52 | 135 |
| 2010 | 2.47 | 138 |
| 2009 | 2.59 | 135 |
| 2008 | 2.51 | 136 |
| 2007 | 2.71 | 137 |
| 2006 | 2.99 | 133 |
| 2005 | 3.15 | 134 |
| 2004 | 3.53 | 133 |
| 2003 | 3.51 | 133 |
| 2002 | 3.76 | 131 |
| 2001 | 4.13 | 128 |
| 2000 | 4.39 | 125 |
| 1999 | 4.79 | 116 |
| 1998 | 4.69 | 119 |
| 1997 | 5.02 | 119 |
| 1996 | 5.53 | 114 |
| 1995 | 5.89 | 114 |
| 1994 | 6.24 | 106 |
| 1993 | 6.5 | 102 |
| 1992 | 7.28 | 100 |
| 1991 | 7.51 | 99 |
| 1990 | 8.42 | 93 |
| 1989 | 9.38 | 83 |
| 1988 | 10.18 | 80 |
| 1987 | 10.29 | 79 |
| 1986 | 11.55 | 73 |