| 时间 | 值 （%） | 世界排名 |
|---|---|---|
| 2016 | 16.81 | 48 |
| 2015 | 16.55 | 86 |
| 2014 | 16.18 | 91 |
| 2013 | 15.38 | 108 |
| 2012 | 12.93 | 131 |
| 2011 | 11.8 | 141 |
| 2010 | 11.18 | 139 |
| 2009 | 13.32 | 120 |
| 2008 | 13.65 | 119 |
| 2007 | 12.88 | 131 |
| 2006 | 15.64 | 103 |
| 2005 | 15.21 | 101 |
| 2004 | 8.86 | 140 |
| 2003 | 8.9 | 134 |
| 2002 | 9.18 | 135 |
| 2001 | 9.52 | 129 |
| 2000 | 9.49 | 126 |
| 1999 | 8.26 | 130 |
| 1998 | 7.55 | 128 |
| 1997 | 9.64 | 111 |
| 1996 | 9.47 | 115 |
| 1995 | 8.86 | 117 |
| 1994 | 7.55 | 117 |
| 1993 | 6.5 | 121 |
| 1992 | 6.39 | 116 |
| 1991 | 5.17 | 117 |
| 1990 | 3.58 | 119 |
| 1989 | 3.05 | 120 |
| 1988 | 3.26 | 116 |
| 1987 | 3.35 | 114 |