| 时间 | 值 （%） | 世界排名 |
|---|---|---|
| 2016 | 4.94 | 28 |
| 2015 | 4.91 | 43 |
| 2014 | 6.65 | 31 |
| 2013 | 10.91 | 10 |
| 2012 | 9.31 | 28 |
| 2011 | 8.86 | 37 |
| 2010 | 11.99 | 11 |
| 2009 | 10.88 | 20 |
| 2008 | 8.35 | 98 |
| 2007 | 6.37 | 72 |
| 2006 | 6.15 | 73 |
| 2005 | 4.25 | 88 |
| 2004 | 3.77 | 84 |
| 2003 | 3.81 | 79 |
| 2002 | 4.39 | 66 |
| 2001 | 3.68 | 92 |
| 2000 | 4.01 | 75 |
| 1999 | 4.67 | 66 |
| 1998 | 13.23 | 31 |
| 1997 | 7.16 | 67 |
| 1996 | 8.98 | 67 |
| 1995 | 10.22 | 70 |
| 1994 | 10.21 | 79 |
| 1993 | 6.36 | 82 |
| 1992 | 11.79 | 52 |
| 1991 | 13.87 | 54 |
| 1990 | 8.97 | 65 |
| 1989 | 3.26 | 105 |
| 1988 | 9.38 | 53 |
| 1987 | 8.8 | 52 |
| 1986 | 8.73 | 55 |