| 时间 | 值 （%） | 世界排名 |
|---|---|---|
| 2016 | 6.17 | 21 |
| 2015 | 6.49 | 21 |
| 2014 | 5.75 | 41 |
| 2013 | 2.14 | 131 |
| 2012 | 5.07 | 59 |
| 2011 | 7.89 | 27 |
| 2010 | 11.73 | 8 |
| 2009 | 6.66 | 19 |
| 2008 | 4.77 | 87 |
| 2007 | 17.93 | 4 |
| 2006 | 6.85 | 70 |
| 2005 | 7.12 | 52 |
| 2004 | 5.9 | 77 |
| 2003 | 7.66 | 37 |
| 2002 | 10.73 | 7 |
| 2001 | 8.2 | 17 |
| 2000 | 6.93 | 30 |
| 1999 | 7.98 | 23 |
| 1998 | 5.91 | 45 |
| 1997 | 5.37 | 69 |
| 1996 | 5.57 | 68 |
| 1995 | 7.07 | 33 |
| 1994 | 4.95 | 66 |
| 1993 | 1.99 | 100 |
| 1992 | 4.6 | 57 |
| 1991 | -.41 | 127 |
| 1990 | 10.88 | 11 |
| 1989 | 7.43 | 25 |
| 1988 | 4.99 | 79 |
| 1987 | 28.7 | 1 |
| 1986 | 11.73 | 6 |