| 时间 | 值 （%） | 世界排名 |
|---|---|---|
| 2016 | 7.741 | 11 |
| 2015 | 9.741 | 6 |
| 2014 | 9.661 | 5 |
| 2013 | 7.66 | 28 |
| 2012 | 8.334 | 27 |
| 2011 | 6.592 | 47 |
| 2010 | 9.947 | 19 |
| 2009 | 11.553 | 10 |
| 2008 | 11.578 | 17 |
| 2007 | 10.833 | 34 |
| 2006 | 10.559 | 27 |
| 2005 | 11.757 | 14 |
| 2004 | 9.254 | 33 |
| 2003 | 7.786 | 25 |
| 2002 | 8.829 | 17 |
| 2001 | 7.124 | 23 |
| 2000 | 5.833 | 46 |
| 1999 | 14.253 | 6 |
| 1998 | 9.251 | 14 |
| 1997 | 11.401 | 13 |
| 1996 | 7.6 | 25 |
| 1995 | 12.197 | 6 |
| 1994 | 5.662 | 38 |
| 1993 | 8.614 | 15 |
| 1992 | 6.003 | 37 |
| 1991 | 6.861 | 23 |
| 1990 | 4.792 | 43 |
| 1989 | 10.741 | 11 |
| 1988 | 4.335 | 52 |
| 1987 | 8.532 | 20 |
| 1986 | 10 | 10 |