| 时间 | 值 （%） | 世界排名 |
|---|---|---|
| 2016 | 15.93 | 34 |
| 2015 | 15.5 | 34 |
| 2014 | 14.94 | 34 |
| 2013 | 14.43 | 34 |
| 2012 | 13.97 | 38 |
| 2011 | 13.56 | 39 |
| 2010 | 13.18 | 39 |
| 2009 | 12.91 | 40 |
| 2008 | 12.66 | 40 |
| 2007 | 12.44 | 43 |
| 2006 | 12.25 | 43 |
| 2005 | 12.1 | 43 |
| 2004 | 11.69 | 47 |
| 2003 | 11.3 | 48 |
| 2002 | 10.94 | 47 |
| 2001 | 10.61 | 47 |
| 2000 | 10.28 | 48 |
| 1999 | 9.92 | 50 |
| 1998 | 9.58 | 51 |
| 1997 | 9.26 | 53 |
| 1996 | 8.95 | 53 |
| 1995 | 8.64 | 54 |
| 1994 | 8.39 | 53 |
| 1993 | 8.16 | 52 |
| 1992 | 7.93 | 53 |
| 1991 | 7.72 | 53 |
| 1990 | 7.52 | 54 |
| 1989 | 7.32 | 54 |
| 1988 | 7.12 | 53 |
| 1987 | 6.92 | 54 |
| 1986 | 6.71 | 55 |