| 时间 | 值 （%） | 世界排名 |
|---|---|---|
| 2014 | 8.53 | 5 |
| 2013 | 5.54 | 48 |
| 2012 | 8.09 | 19 |
| 2011 | 10.67 | 12 |
| 2010 | 7.67 | 37 |
| 2009 | 6.14 | 23 |
| 2008 | 6.61 | 51 |
| 2007 | 7.15 | 64 |
| 2006 | 2.29 | 174 |
| 2005 | 6.34 | 65 |
| 2004 | 2.72 | 158 |
| 2003 | 2.16 | 147 |
| 2002 | -.16 | 174 |
| 2001 | -.12 | 170 |
| 2000 | -2.49 | 193 |
| 1999 | 1.86 | 135 |
| 1998 | -3.77 | 185 |
| 1997 | -3.9 | 185 |
| 1996 | 7.73 | 28 |
| 1995 | -3.31 | 169 |
| 1994 | 5.94 | 44 |
| 1993 | 18.2 | 3 |
| 1992 | 13.85 | 5 |
| 1991 | 9.55 | 10 |
| 1990 | -3.01 | 148 |
| 1989 | -1.42 | 147 |
| 1988 | 2.91 | 109 |
| 1987 | 2.77 | 93 |
| 1986 | 4.69 | 61 |