| 时间 | 值 （%） | 世界排名 |
|---|---|---|
| 2016 | 4.09 | 31 |
| 2015 | 3.13 | 67 |
| 2014 | 5.03 | 51 |
| 2013 | 2.68 | 92 |
| 2012 | 3.68 | 94 |
| 2011 | 8.25 | 47 |
| 2010 | 4.65 | 70 |
| 2009 | 2.59 | 98 |
| 2008 | 10.15 | 75 |
| 2007 | 8.13 | 47 |
| 2006 | 9.59 | 32 |
| 2005 | 6.81 | 64 |
| 2004 | 4.32 | 75 |
| 2003 | 14.24 | 22 |
| 2002 | 10.51 | 32 |
| 2001 | 7.27 | 44 |
| 2000 | 8.98 | 39 |
| 1999 | 6.75 | 49 |
| 1998 | 11.55 | 38 |
| 1997 | 6.95 | 71 |
| 1996 | 9.8 | 62 |
| 1995 | 13.43 | 60 |
| 1994 | 20.57 | 61 |
| 1993 | 18.21 | 47 |
| 1992 | 15.19 | 46 |
| 1991 | 24.23 | 34 |
| 1990 | 37.26 | 17 |
| 1989 | 26.42 | 21 |
| 1988 | 22.59 | 28 |
| 1987 | 21.81 | 25 |
| 1986 | 31.74 | 19 |