| 时间 | 值 （%） | 世界排名 |
|---|---|---|
| 2016 | 7.12 | 81 |
| 2015 | 8.19 | 80 |
| 2014 | 8.14 | 91 |
| 2013 | 4.64 | 127 |
| 2012 | 4.81 | 122 |
| 2011 | 5.48 | 119 |
| 2010 | 5.98 | 127 |
| 2009 | 9.89 | 85 |
| 2008 | 11.96 | 102 |
| 2007 | 10.82 | 131 |
| 2006 | 12.51 | 119 |
| 2005 | 6.99 | 134 |
| 2004 | 6.31 | 131 |
| 2003 | 2.98 | 137 |
| 2002 | 14 | 71 |
| 2001 | 85.2 | 10 |
| 2000 | 25.43 | 40 |
| 1999 | 27.38 | 28 |
| 1998 | 27.03 | 18 |
| 1997 | 14.14 | 89 |
| 1996 | 15.83 | 75 |
| 1995 | 15.59 | 76 |
| 1994 | 18.68 | 77 |
| 1993 | 16.58 | 73 |
| 1992 | 14.94 | 72 |
| 1991 | 21.89 | 47 |
| 1990 | 17.17 | 59 |
| 1989 | 19.82 | 52 |
| 1988 | 21.5 | 50 |
| 1987 | 19.05 | 51 |
| 1986 | 18.44 | 49 |