| 时间 | 值 （%） | 世界排名 |
|---|---|---|
| 2016 | 20.01 | 40 |
| 2015 | 18.77 | 73 |
| 2014 | 19.1 | 76 |
| 2013 | 18.77 | 90 |
| 2012 | 18.15 | 92 |
| 2011 | 18.29 | 90 |
| 2010 | 18.54 | 88 |
| 2009 | 18.42 | 89 |
| 2008 | 21.14 | 74 |
| 2007 | 22.64 | 70 |
| 2006 | 23.25 | 63 |
| 2005 | 23.6 | 61 |
| 2004 | 22.76 | 60 |
| 2003 | 21.79 | 57 |
| 2002 | 20.91 | 60 |
| 2001 | 21.99 | 55 |
| 2000 | 24.42 | 47 |
| 1999 | 33.38 | 30 |
| 1998 | 23.59 | 44 |
| 1997 | 19.18 | 60 |
| 1996 | 20.23 | 55 |
| 1995 | 17.71 | 63 |
| 1994 | 19.7 | 56 |
| 1993 | 19.46 | 54 |
| 1992 | 18.2 | 52 |
| 1991 | 17.1 | 51 |
| 1990 | 15.65 | 59 |
| 1989 | 14.47 | 61 |
| 1988 | 14.08 | 60 |
| 1987 | 12.47 | 61 |
| 1986 | 11.07 | 68 |