| 时间 | 值 （%） | 世界排名 |
|---|---|---|
| 2016 | 8.96 | 63 |
| 2015 | 9.36 | 124 |
| 2014 | 9.61 | 132 |
| 2013 | 9.94 | 144 |
| 2012 | 10.14 | 143 |
| 2011 | 11.21 | 143 |
| 2010 | 10.73 | 142 |
| 2009 | 10.74 | 141 |
| 2008 | 12.38 | 133 |
| 2007 | 10.64 | 144 |
| 2006 | 10.33 | 141 |
| 2005 | 11.81 | 131 |
| 2004 | 12.45 | 116 |
| 2003 | 13.31 | 105 |
| 2002 | 13.66 | 101 |
| 2001 | 12.95 | 106 |
| 2000 | 11.49 | 113 |
| 1999 | 11.35 | 110 |
| 1998 | 10.33 | 112 |
| 1997 | 9.41 | 113 |
| 1996 | 9.29 | 117 |
| 1995 | 9.52 | 108 |
| 1994 | 10.23 | 101 |
| 1993 | 10.66 | 99 |
| 1992 | 10.65 | 91 |
| 1991 | 11.15 | 81 |
| 1990 | 11.85 | 72 |
| 1989 | 11.81 | 71 |
| 1988 | 11.02 | 71 |
| 1987 | 11.43 | 68 |
| 1986 | 13.48 | 58 |