| 时间 | 值 （%） | 世界排名 |
|---|---|---|
| 2016 | 5.4 | 6 |
| 2015 | 4.86 | 8 |
| 2014 | 4.1 | 14 |
| 2013 | 3.96 | 15 |
| 2012 | 3.75 | 14 |
| 2011 | 3.46 | 18 |
| 2010 | 3.85 | 14 |
| 2009 | 4.21 | 14 |
| 2008 | 3.38 | 21 |
| 2007 | 3.35 | 19 |
| 2006 | 3.49 | 18 |
| 2005 | 3.58 | 18 |
| 2004 | 3.55 | 20 |
| 2003 | 3.94 | 19 |
| 2002 | 4.04 | 19 |
| 2001 | 3.81 | 26 |
| 2000 | 3.55 | 27 |
| 1999 | 3.3 | 31 |
| 1998 | 2.94 | 37 |
| 1997 | 4.34 | 19 |
| 1996 | 4.04 | 23 |
| 1995 | 4.07 | 21 |
| 1994 | 4.86 | 17 |
| 1993 | 4.49 | 19 |
| 1992 | 4.76 | 17 |