| 时间 | 值 （%） | 世界排名 |
|---|---|---|
| 2016 | 3.54 | 14 |
| 2015 | 3.28 | 22 |
| 2014 | 3.08 | 26 |
| 2013 | 2.28 | 39 |
| 2012 | 2.16 | 41 |
| 2011 | 2.24 | 39 |
| 2010 | 2.85 | 29 |
| 2009 | 3.26 | 28 |
| 2008 | 2.51 | 40 |
| 2007 | 2.64 | 34 |
| 2006 | 2.56 | 38 |
| 2005 | 2.61 | 37 |
| 2004 | 2.53 | 41 |
| 2003 | 3.71 | 20 |
| 2002 | 3.87 | 21 |
| 2001 | 3.89 | 23 |
| 2000 | 4.07 | 21 |
| 1999 | 5.62 | 11 |
| 1998 | 7.26 | 6 |
| 1997 | 7.1 | 7 |
| 1996 | 6.42 | 7 |
| 1995 | 6.04 | 11 |
| 1994 | 6.41 | 13 |
| 1993 | 5.7 | 15 |
| 1992 | 6.02 | 15 |
| 1991 | 6.63 | 14 |
| 1990 | 6.57 | 15 |
| 1989 | 6.23 | 15 |
| 1988 | 6.63 | 12 |
| 1987 | 3.79 | 35 |
| 1986 | 4.67 | 19 |