| 时间 | 值 （%） | 世界排名 |
|---|---|---|
| 2016 | 6.753 | 18 |
| 2015 | 6.989 | 18 |
| 2014 | 8.728 | 12 |
| 2013 | 8.503 | 18 |
| 2012 | 7.803 | 30 |
| 2011 | 4.839 | 81 |
| 2010 | 3.096 | 111 |
| 2009 | 2.016 | 79 |
| 2008 | 8.876 | 25 |
| 2007 | 9.749 | 40 |
| 2006 | 10.093 | 30 |
| 2005 | 13.018 | 8 |
| 2004 | 13.084 | 13 |
| 2003 | 5.818 | 52 |
| 2002 | 7.677 | 22 |
| 2001 | 11.841 | 8 |
| 2000 | 8.877 | 20 |
| 1999 | 14.586 | 5 |
| 1998 | 4.962 | 48 |
| 1997 | 2.944 | 103 |
| 1996 | 9.188 | 15 |
| 1995 | 8.278 | 18 |
| 1994 | 0.622 | 98 |