| 时间 | 值 （%） | 世界排名 |
|---|---|---|
| 2016 | 7.37 | 11 |
| 2015 | 6.1 | 52 |
| 2014 | 9.7 | 22 |
| 2013 | 4.83 | 52 |
| 2012 | 7.36 | 45 |
| 2011 | 5.48 | 61 |
| 2010 | 6.98 | 45 |
| 2009 | 7.42 | 44 |
| 2008 | 11.79 | 29 |
| 2007 | 12.67 | 29 |
| 2006 | 11.88 | 36 |
| 2005 | 8.28 | 32 |
| 2004 | 7.31 | 34 |
| 2003 | 4.82 | 47 |
| 2002 | 2.38 | 100 |
| 2001 | 1.6 | 110 |
| 2000 | 6.2 | 36 |
| 1999 | 9 | 24 |
| 1998 | 1.73 | 112 |
| 1997 | 2.36 | 81 |
| 1996 | 5.68 | 24 |
| 1995 | 5.37 | 25 |
| 1994 | 0.52 | 113 |
| 1993 | 0.74 | 95 |
| 1992 | 0.13 | 116 |
| 1991 | 0.55 | 84 |
| 1990 | 0.08 | 116 |
| 1989 | 0.07 | 110 |
| 1988 | 0.23 | 93 |
| 1987 | 1.18 | 45 |
| 1986 | 0 | 113 |