| 时间 | 值 （%） | 世界排名 |
|---|---|---|
| 2016 | 4.44 | 8 |
| 2015 | 4.7 | 11 |
| 2014 | 4.18 | 13 |
| 2013 | 3.07 | 27 |
| 2012 | 3.17 | 24 |
| 2011 | 3.57 | 14 |
| 2010 | 3.51 | 19 |
| 2009 | 3.37 | 24 |
| 2008 | 3.14 | 25 |
| 2007 | 2.61 | 35 |
| 2006 | 2.5 | 39 |
| 2005 | 2.65 | 35 |
| 2004 | 2.53 | 42 |
| 2003 | 2.63 | 40 |
| 2002 | 2.62 | 44 |
| 2001 | 2.73 | 43 |
| 2000 | 2.36 | 50 |
| 1999 | 2.77 | 40 |
| 1998 | 2.06 | 58 |
| 1997 | 2.04 | 62 |
| 1996 | 1.68 | 75 |
| 1995 | 1.73 | 77 |
| 1994 | 1.57 | 98 |
| 1993 | 2.18 | 66 |
| 1992 | 3.61 | 30 |
| 1991 | 4.81 | 21 |