| 时间 | 值 （%） | 世界排名 |
|---|---|---|
| 2016 | 0.63 | 4 |
| 2015 | 0.67 | 4 |
| 2014 | 0.84 | 5 |
| 2013 | 0.77 | 4 |
| 2012 | 0.58 | 3 |
| 2011 | 0.66 | 3 |
| 2010 | 1.04 | 6 |
| 2009 | 1.49 | 8 |
| 2008 | 1.18 | 7 |
| 2007 | 1.18 | 6 |
| 2006 | 1.22 | 4 |
| 2005 | 1.35 | 5 |
| 2004 | 1.51 | 5 |
| 2003 | 1.54 | 7 |
| 2002 | 1.76 | 9 |
| 2001 | 2.6 | 21 |
| 2000 | 2.39 | 19 |
| 1999 | 2.96 | 22 |
| 1998 | 3.4 | 29 |
| 1997 | 0.87 | 4 |
| 1996 | 1.07 | 8 |
| 1995 | 1.14 | 8 |
| 1994 | 1.35 | 9 |
| 1993 | 1.5 | 10 |
| 1992 | 1.39 | 8 |
| 1991 | 2.7 | 28 |