| 时间 | 值 （%） | 世界排名 |
|---|---|---|
| 2015 | 17.06 | 12 |
| 2014 | 4.73 | 56 |
| 2013 | 8.73 | 24 |
| 2012 | 4.91 | 63 |
| 2011 | 11.32 | 26 |
| 2010 | 8.39 | 38 |
| 2009 | 4.04 | 76 |
| 2008 | 7.33 | 62 |
| 2007 | 5.47 | 93 |
| 2006 | 6.42 | 69 |
| 2005 | 1.73 | 133 |
| 2004 | 7.93 | 31 |
| 2003 | 2.37 | 97 |
| 2002 | 0.29 | 157 |
| 2001 | 0.33 | 153 |
| 2000 | -.17 | 169 |
| 1999 | 3.56 | 69 |
| 1998 | 6.64 | 32 |
| 1997 | 4.74 | 39 |
| 1996 | 2.58 | 53 |
| 1995 | 5.79 | 20 |
| 1994 | 2.27 | 47 |
| 1993 | 0.49 | 104 |