| 时间 | 值 （%） | 世界排名 |
|---|---|---|
| 2016 | 5.85 | 25 |
| 2015 | 5.71 | 30 |
| 2014 | 5.35 | 47 |
| 2013 | 5.88 | 38 |
| 2012 | 4.56 | 73 |
| 2011 | 6.11 | 55 |
| 2010 | 8.4 | 25 |
| 2009 | 3.31 | 55 |
| 2008 | 0.23 | 171 |
| 2007 | 6.85 | 73 |
| 2006 | 6.47 | 77 |
| 2005 | 5.91 | 77 |
| 2004 | 5.1 | 98 |
| 2003 | 2.93 | 129 |
| 2002 | 0.55 | 157 |
| 2001 | 3.78 | 81 |
| 2000 | 0.6 | 170 |
| 1999 | 2.31 | 126 |
| 1998 | 3.29 | 117 |
| 1997 | 0.47 | 168 |
| 1996 | 4.15 | 99 |
| 1995 | 4.41 | 83 |
| 1994 | 2.63 | 113 |
| 1993 | 0.35 | 123 |
| 1992 | -.8 | 134 |
| 1991 | 1.44 | 102 |
| 1990 | 4.19 | 64 |
| 1989 | 4.69 | 60 |
| 1988 | 6.2 | 53 |
| 1987 | 5.94 | 47 |
| 1986 | 7.18 | 28 |