| 时间 | 值 （%） | 世界排名 |
|---|---|---|
| 2016 | 5.3 | 39 |
| 2015 | 8.13 | 26 |
| 2014 | 3.71 | 79 |
| 2013 | 3.9 | 74 |
| 2012 | 6.77 | 38 |
| 2011 | 4.06 | 93 |
| 2010 | 12.48 | 20 |
| 2009 | 3.46 | 45 |
| 2008 | 6.29 | 52 |
| 2007 | 40.68 | 3 |
| 2006 | 8.84 | 49 |
| 2005 | 3.78 | 94 |
| 2004 | 2.03 | 131 |
| 2003 | 9.61 | 37 |
| 2002 | 16.76 | 10 |
| 2001 | 12.76 | 16 |
| 2000 | 7.26 | 48 |
| 1999 | 15.08 | 10 |
| 1998 | 4.69 | 65 |
| 1997 | -.84 | 129 |
| 1996 | 3.58 | 78 |
| 1995 | 15.96 | 10 |
| 1994 | 7.04 | 42 |
| 1993 | 1.32 | 68 |
| 1992 | 15.03 | 11 |
| 1991 | -2.59 | 96 |
| 1990 | -1.27 | 89 |
| 1989 | 9.79 | 19 |
| 1988 | -.8 | 92 |
| 1987 | 89.22 | 1 |
| 1986 | 26.91 | 6 |