| 时间 | 值 （%） | 世界排名 |
|---|---|---|
| 2016 | 4.98 | 54 |
| 2015 | 4.9 | 52 |
| 2014 | 3.86 | 39 |
| 2013 | 5.1 | 56 |
| 2012 | 5.58 | 64 |
| 2011 | 6.68 | 75 |
| 2010 | 7.45 | 91 |
| 2009 | 6.4 | 68 |
| 2008 | 3.98 | 43 |
| 2007 | 5.07 | 57 |
| 2006 | 7.38 | 97 |
| 2005 | 7.29 | 88 |
| 2004 | 8.17 | 96 |
| 2003 | 7.95 | 90 |
| 2002 | 6.8 | 75 |
| 2001 | 7.3 | 87 |
| 2000 | 8.5 | 100 |
| 1999 | 11.1 | 118 |
| 1998 | 5.41 | 54 |
| 1997 | 7.46 | 87 |
| 1996 | 6.26 | 63 |
| 1995 | 6.39 | 67 |
| 1994 | 6.23 | 69 |
| 1993 | 6.09 | 72 |
| 1992 | 6.66 | 77 |
| 1991 | 7.32 | 96 |