| 时间 | 值 （%） | 世界排名 |
|---|---|---|
| 2016 | 25.96 | 28 |
| 2015 | 27.09 | 44 |
| 2014 | 25.42 | 52 |
| 2013 | 23.91 | 64 |
| 2012 | 22.7 | 69 |
| 2011 | 22 | 72 |
| 2010 | 21.46 | 73 |
| 2009 | 22.92 | 65 |
| 2008 | 22.95 | 69 |
| 2007 | 21.64 | 73 |
| 2006 | 20.44 | 75 |
| 2005 | 19.87 | 76 |
| 2004 | 18.24 | 82 |
| 2003 | 17.15 | 78 |
| 2002 | 17.24 | 80 |
| 2001 | 18.57 | 69 |
| 2000 | 16.9 | 72 |
| 1999 | 15.06 | 81 |
| 1998 | 13.96 | 90 |
| 1997 | 13.81 | 82 |
| 1996 | 12.11 | 89 |
| 1995 | 12.12 | 89 |
| 1994 | 12.24 | 85 |
| 1993 | 12.11 | 90 |
| 1992 | 12.37 | 79 |
| 1991 | 11.79 | 78 |
| 1990 | 11.83 | 73 |
| 1989 | 11.87 | 70 |
| 1988 | 11.22 | 69 |
| 1987 | 10.77 | 74 |
| 1986 | 10.19 | 73 |