| 时间 | 值 （%） | 世界排名 |
|---|---|---|
| 2016 | 2.7 | 103 |
| 2015 | 2.89 | 124 |
| 2014 | 3.13 | 126 |
| 2013 | 3.14 | 131 |
| 2012 | 3.35 | 127 |
| 2011 | 3.52 | 123 |
| 2010 | 3.99 | 118 |
| 2009 | 4.22 | 119 |
| 2008 | 4.92 | 111 |
| 2007 | 5.34 | 108 |
| 2006 | 5.95 | 105 |
| 2005 | 6.27 | 103 |
| 2004 | 6.68 | 103 |
| 2003 | 7.14 | 103 |
| 2002 | 6.93 | 104 |
| 2001 | 6.94 | 105 |
| 2000 | 6.5 | 106 |
| 1999 | 6.27 | 107 |
| 1998 | 6.69 | 107 |
| 1997 | 6.55 | 108 |
| 1996 | 6.71 | 111 |
| 1995 | 6.76 | 112 |
| 1994 | 6.74 | 103 |
| 1993 | 6.87 | 101 |
| 1992 | 7.15 | 101 |
| 1991 | 7.9 | 96 |
| 1990 | 8.35 | 94 |
| 1989 | 8.72 | 86 |
| 1988 | 8.13 | 86 |
| 1987 | 7.67 | 86 |
| 1986 | 7.6 | 82 |