| 时间 | 值 （%） | 世界排名 |
|---|---|---|
| 2016 | 6.98 | 24 |
| 2015 | 13.03 | 10 |
| 2014 | 1.7 | 90 |
| 2013 | 6.06 | 38 |
| 2012 | 6.86 | 40 |
| 2011 | 4.15 | 51 |
| 2010 | 3.61 | 64 |
| 2009 | 8.66 | 44 |
| 2008 | 8.55 | 34 |
| 2007 | 8.15 | 36 |
| 2006 | -2.02 | 134 |
| 2005 | -.78 | 126 |
| 2004 | 0.58 | 112 |
| 2003 | 6.01 | 34 |
| 2002 | 1.64 | 103 |
| 2001 | 2.77 | 90 |
| 2000 | -2.24 | 116 |
| 1999 | -2.38 | 113 |
| 1998 | 3.56 | 56 |
| 1997 | -.45 | 105 |
| 1996 | 2.71 | 62 |
| 1995 | 9.83 | 11 |
| 1994 | 29.39 | 5 |
| 1993 | 7.5 | 23 |
| 1992 | 9.12 | 19 |
| 1991 | 5.82 | 35 |
| 1990 | 4.6 | 31 |
| 1989 | 1.43 | 65 |
| 1988 | 1.86 | 51 |
| 1987 | 3.24 | 44 |
| 1986 | 7.15 | 23 |