| 时间 | 值 （%） | 世界排名 |
|---|---|---|
| 2016 | 7.172 | 22 |
| 2015 | 6.153 | 41 |
| 2014 | 5.801 | 47 |
| 2013 | 5.153 | 54 |
| 2012 | 5.437 | 56 |
| 2011 | 5.673 | 56 |
| 2010 | 6.465 | 48 |
| 2009 | 8.537 | 39 |
| 2008 | 11.613 | 15 |
| 2007 | 9.153 | 25 |
| 2006 | 7.138 | 48 |
| 2005 | 6.043 | 56 |
| 2004 | 6.553 | 46 |
| 2003 | 9.76 | 31 |
| 2002 | 10.774 | 27 |
| 2001 | 9.371 | 44 |
| 2000 | 9.196 | 54 |
| 1999 | 12.241 | 36 |
| 1998 | 16.496 | 28 |
| 1997 | 15.375 | 33 |
| 1996 | 14.908 | 40 |
| 1995 | 13.542 | 45 |
| 1994 | 11.113 | 47 |
| 1993 | 11.504 | 46 |
| 1992 | 13.779 | 40 |
| 1991 | 17.304 | 32 |
| 1990 | 18.863 | 27 |
| 1989 | 18.125 | 22 |
| 1988 | 13.542 | 26 |
| 1987 | 8.7 | 47 |
| 1986 | 10.975 | 34 |