| 时间 | 值 （%） | 世界排名 |
|---|---|---|
| 2015 | 4.18 | 65 |
| 2014 | 1.63 | 130 |
| 2013 | 7.41 | 32 |
| 2012 | 7.73 | 42 |
| 2011 | 7.72 | 41 |
| 2010 | 9.01 | 33 |
| 2009 | 5.27 | 59 |
| 2008 | 6.2 | 71 |
| 2007 | 6.49 | 78 |
| 2006 | 9.89 | 38 |
| 2005 | 3.36 | 93 |
| 2004 | 5.44 | 52 |
| 2003 | 5.73 | 39 |
| 2002 | 5.39 | 40 |
| 2001 | 6.98 | 29 |
| 2000 | 7.45 | 29 |
| 1999 | 5 | 51 |
| 1998 | 7.77 | 26 |
| 1997 | 11.81 | 11 |
| 1996 | 13.35 | 6 |
| 1995 | 13.27 | 4 |
| 1994 | 13.58 | 4 |
| 1993 | 13.81 | 5 |
| 1992 | 13.49 | 3 |
| 1991 | 13.49 | 2 |
| 1990 | 8.28 | 7 |
| 1989 | 6.35 | 10 |
| 1988 | 7.28 | 8 |
| 1987 | 9.85 | 5 |
| 1986 | 1.7 | 25 |