| 时间 | 值 （%） | 世界排名 |
|---|---|---|
| 2016 | 4.32 | 41 |
| 2015 | 2.99 | 67 |
| 2014 | 3.05 | 65 |
| 2013 | 3.26 | 66 |
| 2012 | 3.37 | 71 |
| 2011 | 2.21 | 77 |
| 2010 | 3.85 | 58 |
| 2009 | 5.24 | 69 |
| 2008 | 5.08 | 57 |
| 2007 | 6.06 | 56 |
| 2006 | 7.37 | 43 |
| 2005 | 4.53 | 57 |
| 2004 | 4.53 | 52 |
| 2003 | 3.76 | 59 |
| 2002 | 5.61 | 43 |
| 2001 | 6.22 | 40 |
| 2000 | 0.88 | 99 |
| 1999 | 4.87 | 39 |
| 1998 | 3.65 | 53 |
| 1997 | 2.15 | 75 |
| 1996 | 7.28 | 25 |
| 1995 | 3.39 | 45 |
| 1994 | 3.36 | 44 |
| 1993 | 4.87 | 38 |
| 1992 | 6.44 | 22 |
| 1991 | 5.03 | 38 |
| 1990 | 11.06 | 8 |
| 1989 | 11.32 | 11 |
| 1988 | 8.53 | 13 |
| 1987 | 7.16 | 19 |
| 1986 | 5.24 | 30 |