| 时间 | 值 （%） | 世界排名 |
|---|---|---|
| 2016 | 20.76 | 3 |
| 2015 | 3.34 | 62 |
| 2014 | 9.6 | 16 |
| 2013 | 0.57 | 116 |
| 2012 | 0.61 | 111 |
| 2011 | 6.86 | 34 |
| 2010 | 5.77 | 37 |
| 2009 | 13.88 | 24 |
| 2008 | 10.38 | 26 |
| 2007 | 9.57 | 29 |
| 2006 | 3.78 | 80 |
| 2005 | 8.88 | 33 |
| 2004 | 3.98 | 63 |
| 2003 | 2.78 | 77 |
| 2002 | -.19 | 114 |
| 2001 | 2.35 | 95 |
| 2000 | 1.38 | 90 |
| 1999 | 9.64 | 19 |
| 1998 | 12.19 | 19 |
| 1997 | 11.25 | 20 |
| 1996 | 4.64 | 40 |
| 1995 | 7.8 | 18 |
| 1994 | 1.38 | 66 |
| 1993 | 5.94 | 32 |
| 1992 | 3.45 | 41 |
| 1991 | -.17 | 84 |
| 1990 | 3.4 | 38 |
| 1989 | 5.34 | 33 |
| 1988 | 5.48 | 20 |
| 1987 | 8.19 | 15 |
| 1986 | 9.4 | 13 |