| 时间 | 值 （%） | 世界排名 |
|---|---|---|
| 2016 | 6.8 | 20 |
| 2015 | 4.81 | 57 |
| 2014 | 4.53 | 67 |
| 2013 | 0.75 | 124 |
| 2012 | 2.55 | 85 |
| 2011 | 4.51 | 82 |
| 2010 | 3.42 | 109 |
| 2009 | -5.21 | 106 |
| 2008 | 8.47 | 33 |
| 2007 | 7.73 | 55 |
| 2006 | 4.11 | 105 |
| 2005 | 12.12 | 19 |
| 2004 | 16.26 | 12 |
| 2003 | 4.24 | 82 |
| 2002 | 2.7 | 95 |
| 2001 | 4.13 | 62 |
| 2000 | 1.27 | 126 |
| 1999 | 4.92 | 63 |
| 1998 | 6.12 | 47 |
| 1997 | -.33 | 124 |
| 1996 | 4.72 | 68 |
| 1995 | 4.14 | 67 |
| 1994 | 3.88 | 72 |
| 1993 | 4.9 | 44 |
| 1992 | 7.16 | 35 |
| 1991 | 5.13 | 37 |
| 1990 | 6.43 | 36 |
| 1989 | 4.65 | 54 |
| 1988 | 9.82 | 21 |
| 1987 | 8.65 | 26 |
| 1986 | 8.1 | 27 |