| 时间 | 值 （%） | 世界排名 |
|---|---|---|
| 2016 | 9.64 | 11 |
| 2015 | 8.67 | 20 |
| 2014 | 8.88 | 13 |
| 2013 | 8.58 | 18 |
| 2012 | 8.1 | 35 |
| 2011 | 8.09 | 48 |
| 2010 | 6.68 | 43 |
| 2009 | 7.1 | 39 |
| 2008 | 7.86 | 106 |
| 2007 | 8.11 | 48 |
| 2006 | 6.4 | 69 |
| 2005 | 4.7 | 83 |
| 2004 | 9.16 | 34 |
| 2003 | 19.38 | 13 |
| 2002 | 13.97 | 22 |
| 2001 | 4.36 | 80 |
| 2000 | 4.76 | 62 |
| 1999 | 5.66 | 60 |
| 1998 | 10.81 | 40 |
| 1997 | 19.82 | 25 |
| 1996 | 28.34 | 25 |
| 1995 | 42.25 | 26 |
| 1994 | 44.74 | 26 |
| 1993 | 54.1 | 22 |
| 1992 | 68.46 | 15 |
| 1991 | 101.97 | 11 |
| 1990 | 112.53 | 6 |
| 1989 | 80.45 | 10 |
| 1988 | 62.19 | 10 |
| 1987 | 63.57 | 9 |
| 1986 | 76.38 | 9 |