| 时间 | 值 （%） | 世界排名 |
|---|---|---|
| 2016 | 4.2 | 100 |
| 2015 | 4.42 | 111 |
| 2014 | 4.65 | 125 |
| 2013 | 7.32 | 106 |
| 2012 | 10.37 | 77 |
| 2011 | 15.12 | 53 |
| 2010 | 10.94 | 92 |
| 2009 | 6.76 | 109 |
| 2008 | 9.16 | 115 |
| 2007 | 6.25 | 151 |
| 2006 | 8.16 | 141 |
| 2005 | 6.09 | 142 |
| 2004 | 5.57 | 138 |
| 2003 | 14.71 | 69 |
| 2002 | 3.78 | 134 |
| 2001 | 5.46 | 128 |
| 2000 | 4.91 | 126 |
| 1999 | 3.8 | 139 |
| 1998 | 10.07 | 89 |
| 1997 | 19.55 | 64 |
| 1996 | 10.62 | 98 |
| 1995 | 17.74 | 69 |
| 1994 | 10.69 | 105 |
| 1993 | 18.99 | 65 |
| 1992 | 15.51 | 70 |
| 1991 | 19.4 | 53 |
| 1990 | 25.52 | 38 |
| 1989 | 26.18 | 34 |
| 1988 | 17.96 | 60 |
| 1987 | 19.43 | 48 |
| 1986 | 13.62 | 64 |