| 时间 | 值 （%） | 世界排名 |
|---|---|---|
| 2015 | 9.94 | 75 |
| 2014 | 9.8 | 75 |
| 2013 | 10.29 | 72 |
| 2012 | 10.12 | 71 |
| 2011 | 10.2 | 74 |
| 2010 | 10.63 | 71 |
| 2009 | 9.66 | 82 |
| 2008 | 10.44 | 75 |
| 2007 | 11.17 | 72 |
| 2006 | 11.62 | 71 |
| 2005 | 11.42 | 75 |
| 2004 | 10.08 | 87 |
| 2003 | 13.02 | 71 |
| 2002 | 13.16 | 73 |
| 2001 | 12.69 | 75 |
| 2000 | 12.84 | 75 |
| 1999 | 13.4 | 76 |
| 1998 | 13.18 | 81 |
| 1997 | 12.99 | 80 |
| 1996 | 14.22 | 76 |
| 1995 | 12.01 | 86 |
| 1994 | 13.39 | 79 |
| 1993 | 10.19 | 88 |
| 1992 | 8.99 | 91 |
| 1991 | 11.45 | 83 |
| 1990 | 10.4 | 87 |
| 1989 | 15.3 | 65 |
| 1988 | 16.11 | 66 |
| 1987 | 16.48 | 59 |
| 1986 | 22.17 | 44 |