| 时间 | 值 （%） | 世界排名 |
|---|---|---|
| 2016 | 5.59 | 32 |
| 2015 | 8.76 | 19 |
| 2014 | 7.47 | 31 |
| 2013 | 3.79 | 76 |
| 2012 | 3.27 | 71 |
| 2011 | 7.81 | 46 |
| 2010 | 7.55 | 58 |
| 2009 | 9.16 | 21 |
| 2008 | 4.44 | 70 |
| 2007 | 9.67 | 35 |
| 2006 | 12.17 | 33 |
| 2005 | 9.72 | 32 |
| 2004 | 9.81 | 40 |
| 2003 | 7.32 | 53 |
| 2002 | 7.21 | 41 |
| 2001 | 2.61 | 79 |
| 2000 | 6.03 | 63 |
| 1999 | 5.96 | 49 |
| 1998 | 4.15 | 75 |
| 1997 | 4.01 | 82 |
| 1996 | 6.39 | 48 |
| 1995 | 11.29 | 18 |
| 1994 | 9.16 | 27 |
| 1993 | 5.5 | 39 |
| 1992 | 3.22 | 55 |
| 1991 | 0.34 | 78 |
| 1990 | 7.33 | 31 |
| 1989 | 8.3 | 23 |
| 1988 | 9.1 | 27 |
| 1987 | 5.57 | 42 |
| 1986 | 5.76 | 43 |