| 时间 | 值 （%） | 世界排名 |
|---|---|---|
| 2016 | 0.31 | 112 |
| 2015 | 0.35 | 110 |
| 2014 | 0.39 | 108 |
| 2013 | 0.44 | 107 |
| 2012 | 0.48 | 101 |
| 2011 | 0.54 | 100 |
| 2010 | 0.59 | 103 |
| 2009 | 0.65 | 101 |
| 2008 | 0.69 | 99 |
| 2007 | 0.72 | 99 |
| 2006 | 0.74 | 97 |
| 2005 | 0.76 | 98 |
| 2004 | 0.76 | 99 |
| 2003 | 0.79 | 93 |
| 2002 | 0.85 | 91 |
| 2001 | 0.93 | 86 |
| 2000 | 1.02 | 82 |
| 1999 | 1.1 | 79 |
| 1998 | 1.2 | 77 |
| 1997 | 1.29 | 74 |
| 1996 | 1.38 | 77 |
| 1995 | 1.49 | 68 |
| 1994 | 1.59 | 65 |
| 1993 | 1.67 | 64 |
| 1992 | 1.7 | 62 |
| 1991 | 1.7 | 64 |
| 1990 | 1.68 | 63 |
| 1989 | 1.66 | 72 |
| 1988 | 1.68 | 65 |
| 1987 | 1.75 | 68 |
| 1986 | 1.85 | 64 |