| 时间 | 值 （%） | 世界排名 |
|---|---|---|
| 2016 | 13.55 | 33 |
| 2015 | 12.35 | 51 |
| 2014 | 11.58 | 61 |
| 2013 | 13.29 | 60 |
| 2012 | 17.24 | 35 |
| 2011 | 12.6 | 68 |
| 2010 | 14.57 | 66 |
| 2009 | 17.61 | 44 |
| 2008 | 6.52 | 133 |
| 2007 | 17.44 | 86 |
| 2006 | 45.53 | 12 |
| 2005 | 16.53 | 71 |
| 2004 | 20.51 | 47 |
| 2003 | 17.54 | 56 |
| 2002 | 16.84 | 57 |
| 2001 | 11.75 | 91 |
| 2000 | 12.13 | 87 |
| 1999 | 4.31 | 135 |
| 1998 | 7.86 | 99 |
| 1997 | 19.91 | 60 |
| 1996 | 20.07 | 57 |
| 1995 | 13.81 | 84 |
| 1994 | 17.37 | 81 |
| 1993 | 18.13 | 67 |
| 1992 | 29.3 | 38 |
| 1991 | 18.94 | 55 |
| 1990 | 11.64 | 73 |
| 1989 | 7.4 | 99 |
| 1988 | 7.7 | 92 |
| 1987 | 16.4 | 59 |
| 1986 | 16.07 | 56 |