| 时间 | 值 （%） | 世界排名 |
|---|---|---|
| 2015 | 11.9 | 17 |
| 2014 | 9.58 | 24 |
| 2013 | 9.52 | 20 |
| 2012 | 8.9 | 32 |
| 2011 | 11.6 | 24 |
| 2010 | 16.08 | 16 |
| 2009 | 22.52 | 5 |
| 2008 | 6.63 | 68 |
| 2007 | 6.76 | 76 |
| 2006 | 7.11 | 59 |
| 2005 | 5.16 | 67 |
| 2004 | 5.17 | 55 |
| 2003 | 3.78 | 58 |
| 2002 | 6.19 | 31 |
| 2001 | 4.81 | 47 |
| 2000 | 4.51 | 62 |
| 1999 | 5.1 | 50 |
| 1998 | 2.39 | 93 |
| 1997 | 4.4 | 43 |
| 1996 | 4.54 | 32 |
| 1995 | 9.39 | 11 |
| 1994 | 4.02 | 26 |
| 1993 | 2.48 | 33 |