| 时间 | 值 （%） | 世界排名 |
|---|---|---|
| 2016 | 49.4 | 77 |
| 2015 | 41.03 | 109 |
| 2014 | 42.22 | 101 |
| 2013 | 39.5 | 100 |
| 2012 | 37.5 | 103 |
| 2011 | 35.56 | 116 |
| 2010 | 34.76 | 118 |
| 2009 | 33.21 | 117 |
| 2008 | 31.39 | 119 |
| 2007 | 30.68 | 118 |
| 2006 | 28.8 | 116 |
| 2005 | 28.74 | 113 |
| 2004 | 27.27 | 117 |
| 2003 | 24.74 | 121 |
| 2002 | 23.84 | 121 |
| 2001 | 20.43 | 126 |
| 2000 | 20.71 | 123 |
| 1999 | 13.15 | 147 |
| 1998 | 18.76 | 123 |
| 1997 | 22.29 | 111 |
| 1996 | 22.81 | 105 |
| 1995 | 20.95 | 109 |
| 1994 | 21.11 | 116 |
| 1993 | 18.2 | 125 |
| 1992 | 12.98 | 129 |
| 1991 | 13.24 | 126 |
| 1990 | 13.92 | 121 |
| 1989 | 10.16 | 119 |
| 1988 | 11.71 | 117 |
| 1987 | 13.8 | 117 |
| 1986 | 13.26 | 114 |