| 时间 | 值 （%） | 世界排名 |
|---|---|---|
| 2016 | 7.02 | 9 |
| 2015 | 7.27 | 10 |
| 2014 | 7.61 | 12 |
| 2013 | 8.02 | 16 |
| 2012 | 8.03 | 20 |
| 2011 | 8.04 | 25 |
| 2010 | 8.53 | 20 |
| 2009 | 7.5 | 15 |
| 2008 | 7.82 | 30 |
| 2007 | 7.6 | 59 |
| 2006 | 8.62 | 35 |
| 2005 | 7.11 | 53 |
| 2004 | 6.36 | 69 |
| 2003 | 6.07 | 58 |
| 2002 | 5.92 | 36 |
| 2001 | 5.75 | 36 |
| 2000 | 5.8 | 55 |
| 1999 | 7.31 | 29 |
| 1998 | 3.97 | 91 |
| 1997 | 6.87 | 40 |
| 1996 | 6.93 | 42 |
| 1995 | 7.03 | 34 |
| 1994 | 8.16 | 22 |
| 1993 | 5.91 | 42 |
| 1992 | 5.56 | 49 |
| 1991 | 4.3 | 56 |
| 1990 | 6.7 | 32 |
| 1989 | 14.19 | 2 |
| 1988 | -2.01 | 151 |
| 1987 | -1.43 | 144 |
| 1986 | 4.89 | 56 |