| 时间 | 值 （%） | 世界排名 |
|---|---|---|
| 2016 | 2.33 | 83 |
| 2015 | 2.34 | 84 |
| 2014 | 2.35 | 80 |
| 2013 | 2.36 | 82 |
| 2012 | 2.39 | 82 |
| 2011 | 2.42 | 80 |
| 2010 | 2.48 | 78 |
| 2009 | 2.54 | 75 |
| 2008 | 2.6 | 77 |
| 2007 | 2.65 | 78 |
| 2006 | 2.68 | 78 |
| 2005 | 2.73 | 77 |
| 2004 | 2.77 | 74 |
| 2003 | 2.81 | 72 |
| 2002 | 2.86 | 74 |
| 2001 | 2.64 | 82 |
| 2000 | 2.55 | 82 |
| 1999 | 2.59 | 81 |
| 1998 | 2.63 | 81 |
| 1997 | 2.66 | 81 |
| 1996 | 2.68 | 83 |
| 1995 | 2.71 | 83 |
| 1994 | 2.74 | 86 |
| 1993 | 2.76 | 85 |
| 1992 | 2.8 | 87 |
| 1991 | 2.94 | 88 |
| 1990 | 3.03 | 90 |
| 1989 | 3.07 | 90 |
| 1988 | 3.11 | 94 |
| 1987 | 3.14 | 97 |
| 1986 | 3.18 | 97 |