| 时间 | 值 （%） | 世界排名 |
|---|---|---|
| 2016 | 2.56 | 39 |
| 2015 | 2.88 | 90 |
| 2014 | 2.12 | 116 |
| 2013 | 3.77 | 77 |
| 2012 | 1.77 | 133 |
| 2011 | 2.11 | 125 |
| 2010 | 2.59 | 109 |
| 2009 | 2.02 | 122 |
| 2008 | 2.67 | 130 |
| 2007 | 3.11 | 129 |
| 2006 | 2.19 | 133 |
| 2005 | 3 | 99 |
| 2004 | 3.23 | 91 |
| 2003 | 2.55 | 91 |
| 2002 | 3.24 | 77 |
| 2001 | 4.15 | 57 |
| 2000 | 2.69 | 97 |
| 1999 | 2.4 | 93 |
| 1998 | 2.54 | 88 |
| 1997 | 2.67 | 71 |
| 1996 | 2.31 | 59 |
| 1995 | 2.77 | 50 |
| 1994 | 2.08 | 53 |
| 1993 | 0.87 | 88 |
| 1992 | 1.21 | 61 |
| 1991 | 1.51 | 45 |
| 1990 | 0.97 | 67 |
| 1989 | 1.25 | 49 |
| 1988 | 1.1 | 48 |
| 1987 | 0.84 | 60 |
| 1986 | 1.57 | 28 |