| 时间 | 值 （%） | 世界排名 |
|---|---|---|
| 2016 | 5.96 | 5 |
| 2015 | 5.37 | 15 |
| 2014 | 4.84 | 21 |
| 2013 | 4.77 | 29 |
| 2012 | 5.28 | 29 |
| 2011 | 5.25 | 40 |
| 2010 | 4.4 | 58 |
| 2009 | 3.89 | 21 |
| 2008 | 4.83 | 53 |
| 2007 | 5.77 | 63 |
| 2006 | 5.25 | 72 |
| 2005 | 4.96 | 60 |
| 2004 | 3.54 | 100 |
| 2003 | 2.92 | 90 |
| 2002 | 1.94 | 86 |
| 2001 | 3.1 | 58 |
| 2000 | 3.25 | 91 |
| 1999 | 2.58 | 81 |
| 1998 | 3.02 | 82 |
| 1997 | 2.31 | 103 |
| 1996 | 2.31 | 102 |
| 1995 | 2.89 | 72 |
| 1994 | 1.67 | 93 |
| 1993 | 2.43 | 62 |
| 1992 | 3.08 | 53 |
| 1991 | 1.07 | 78 |
| 1990 | 3.05 | 58 |
| 1989 | 0.23 | 111 |
| 1988 | -.25 | 121 |
| 1987 | 1.03 | 92 |
| 1986 | 1.41 | 90 |