| 时间 | 值 （%） | 世界排名 |
|---|---|---|
| 2015 | 3.4 | 79 |
| 2014 | 5.61 | 50 |
| 2013 | 5.37 | 47 |
| 2012 | 4.89 | 64 |
| 2011 | 5.15 | 65 |
| 2010 | 6.39 | 50 |
| 2009 | 10.13 | 25 |
| 2008 | 12.87 | 20 |
| 2007 | 15.32 | 25 |
| 2006 | 23.54 | 8 |
| 2005 | 15.76 | 13 |
| 2004 | 8.21 | 30 |
| 2003 | 5.36 | 44 |
| 2002 | 2.49 | 96 |
| 2001 | 3.05 | 75 |
| 2000 | 10.79 | 11 |
| 1999 | 1.94 | 98 |
| 1998 | 3.92 | 54 |
| 1997 | 4.98 | 36 |
| 1996 | 0.22 | 150 |
| 1995 | 0.2 | 146 |
| 1994 | 0.05 | 139 |
| 1993 | -.6 | 149 |
| 1992 | 0.77 | 75 |
| 1991 | -.27 | 143 |
| 1990 | 0.9 | 70 |
| 1989 | -.03 | 124 |
| 1988 | 0.38 | 83 |
| 1987 | 0.58 | 71 |
| 1986 | 0.36 | 77 |