| 时间 | 值 （%） | 世界排名 |
|---|---|---|
| 2015 | 0.8 | 155 |
| 2014 | 2.76 | 102 |
| 2013 | 16.37 | 13 |
| 2012 | 34.76 | 7 |
| 2011 | 43.91 | 3 |
| 2010 | 23.53 | 8 |
| 2009 | 13.6 | 13 |
| 2008 | 15.02 | 18 |
| 2007 | 8.8 | 53 |
| 2006 | 7.19 | 58 |
| 2005 | 7.43 | 36 |
| 2004 | 4.66 | 57 |
| 2003 | 8.24 | 24 |
| 2002 | 5.57 | 37 |
| 2001 | 3.39 | 72 |
| 2000 | 4.72 | 58 |
| 1999 | 2.87 | 86 |
| 1998 | 1.68 | 114 |
| 1997 | 2.12 | 90 |
| 1996 | 1.18 | 97 |
| 1995 | 0.67 | 110 |
| 1994 | 0.75 | 102 |
| 1993 | 1 | 83 |
| 1992 | 0.15 | 114 |
| 1991 | 0.47 | 92 |
| 1986 | 0 | 107 |