| 时间 | 值 （%） | 世界排名 |
|---|---|---|
| 2016 | 2.1 | 21 |
| 2015 | 2.37 | 17 |
| 2014 | 2.63 | 13 |
| 2013 | 2.77 | 11 |
| 2012 | 2.75 | 12 |
| 2011 | 2.58 | 20 |
| 2010 | 2.31 | 24 |
| 2009 | 2.09 | 35 |
| 2008 | 2.04 | 39 |
| 2007 | 2.3 | 29 |
| 2006 | 2.78 | 17 |
| 2005 | 3.44 | 10 |
| 2004 | 4.05 | 6 |
| 2003 | 4.4 | 3 |
| 2002 | 4.31 | 3 |
| 2001 | 3.85 | 4 |
| 2000 | 3.1 | 14 |
| 1999 | 2.43 | 29 |
| 1998 | 2.21 | 36 |
| 1997 | 2.71 | 23 |
| 1996 | 3.77 | 5 |
| 1995 | 5.21 | 5 |
| 1994 | 6.53 | 2 |
| 1993 | 7.31 | 1 |
| 1992 | 6.97 | 2 |
| 1991 | 5.56 | 3 |
| 1990 | 3.59 | 8 |
| 1989 | 1.7 | 70 |
| 1988 | 0 | 140 |
| 1987 | -1.18 | 178 |
| 1986 | -1.88 | 189 |