| 时间 | 值 （%） | 世界排名 |
|---|---|---|
| 2016 | 24.46 | 30 |
| 2015 | 24.16 | 55 |
| 2014 | 25.66 | 51 |
| 2013 | 21.71 | 71 |
| 2012 | 21.41 | 75 |
| 2011 | 19.21 | 83 |
| 2010 | 19.71 | 81 |
| 2009 | 23.02 | 63 |
| 2008 | 25.43 | 59 |
| 2007 | 26.73 | 54 |
| 2006 | 27.23 | 52 |
| 2005 | 26.06 | 53 |
| 2004 | 27.74 | 45 |
| 2003 | 25.55 | 47 |
| 2002 | 24.02 | 50 |
| 2001 | 28.47 | 36 |
| 2000 | 29.24 | 33 |
| 1999 | 24.18 | 44 |
| 1998 | 29.77 | 32 |
| 1997 | 23.89 | 40 |
| 1996 | 25.84 | 33 |
| 1995 | 20.74 | 52 |
| 1994 | 25.81 | 36 |
| 1993 | 22.17 | 47 |
| 1992 | 21.6 | 39 |
| 1991 | 8.09 | 101 |
| 1990 | 6.96 | 108 |
| 1989 | 9.13 | 86 |
| 1988 | 8.17 | 88 |
| 1987 | 6.47 | 102 |
| 1986 | 7.85 | 94 |