| 时间 | 值 （%） | 世界排名 |
|---|---|---|
| 2016 | 9.52 | 10 |
| 2015 | 9.33 | 19 |
| 2014 | 4.32 | 48 |
| 2013 | 7.57 | 29 |
| 2012 | 8.79 | 30 |
| 2011 | 12.95 | 16 |
| 2010 | 9.55 | 22 |
| 2009 | 10.69 | 38 |
| 2008 | 8.89 | 32 |
| 2007 | 13.57 | 23 |
| 2006 | 14.48 | 11 |
| 2005 | 15.33 | 8 |
| 2004 | 8.22 | 25 |
| 2003 | 5.83 | 36 |
| 2002 | 8.48 | 27 |
| 2001 | 7.36 | 32 |
| 2000 | 14.72 | 11 |
| 1999 | 21.28 | 6 |
| 1998 | 19.42 | 10 |
| 1997 | 14.1 | 15 |
| 1996 | 11.57 | 16 |
| 1995 | 3.17 | 49 |
| 1994 | 8.59 | 15 |
| 1993 | 21.9 | 4 |
| 1992 | 29.21 | 3 |
| 1991 | 21.81 | 7 |