| 时间 | 值 （%） | 世界排名 |
|---|---|---|
| 2016 | 13.31 | 50 |
| 2015 | 14.55 | 53 |
| 2014 | 14.72 | 56 |
| 2013 | 15.13 | 56 |
| 2012 | 12.67 | 61 |
| 2011 | 11.79 | 65 |
| 2010 | 13.07 | 60 |
| 2009 | 19.63 | 42 |
| 2008 | 21.41 | 43 |
| 2007 | 20.46 | 45 |
| 2006 | 19.62 | 48 |
| 2005 | 22.06 | 43 |
| 2004 | 22.61 | 43 |
| 2003 | 20.76 | 49 |
| 2002 | 21.5 | 48 |
| 2001 | 26.35 | 32 |
| 2000 | 30.88 | 27 |
| 1999 | 34.76 | 23 |
| 1998 | 35.09 | 23 |
| 1997 | 34.73 | 25 |
| 1996 | 40.98 | 16 |
| 1995 | 34.36 | 28 |
| 1994 | 29.29 | 39 |
| 1993 | 27.85 | 41 |
| 1992 | 27.19 | 43 |
| 1991 | 13.1 | 78 |
| 1990 | 12.86 | 79 |
| 1989 | 15.52 | 64 |
| 1988 | 16.63 | 61 |
| 1987 | 16.42 | 60 |
| 1986 | 18.67 | 53 |