| 时间 | 值 （%） | 世界排名 |
|---|---|---|
| 2016 | 3.14 | 53 |
| 2015 | 3.28 | 48 |
| 2014 | 3.4 | 48 |
| 2013 | 3.45 | 49 |
| 2012 | 3.37 | 50 |
| 2011 | 3.18 | 57 |
| 2010 | 2.94 | 71 |
| 2009 | 2.73 | 73 |
| 2008 | 2.59 | 78 |
| 2007 | 2.55 | 80 |
| 2006 | 2.6 | 80 |
| 2005 | 2.67 | 78 |
| 2004 | 2.73 | 75 |
| 2003 | 2.8 | 73 |
| 2002 | 2.87 | 72 |
| 2001 | 2.95 | 67 |
| 2000 | 3.04 | 67 |
| 1999 | 3.13 | 66 |
| 1998 | 3.09 | 69 |
| 1997 | 2.86 | 74 |
| 1996 | 2.83 | 79 |
| 1995 | 2.8 | 78 |
| 1994 | 2.76 | 85 |
| 1993 | 2.69 | 90 |
| 1992 | 2.57 | 98 |
| 1991 | 2.41 | 112 |
| 1990 | 2.22 | 115 |
| 1989 | 2.04 | 125 |
| 1988 | 2.27 | 122 |
| 1987 | 3.09 | 98 |
| 1986 | 3.2 | 95 |