| 时间 | 值 （%） | 世界排名 |
|---|---|---|
| 2016 | 0.54 | 86 |
| 2015 | 0.33 | 125 |
| 2014 | 0.91 | 123 |
| 2013 | 1.3 | 137 |
| 2012 | 0.88 | 168 |
| 2011 | 4.43 | 104 |
| 2010 | 2.3 | 119 |
| 2009 | 2.12 | 109 |
| 2008 | 3.96 | 154 |
| 2007 | 2.38 | 136 |
| 2006 | 3.37 | 111 |
| 2005 | 3.04 | 114 |
| 2004 | 2.29 | 116 |
| 2003 | 1.12 | 139 |
| 2002 | 2.66 | 98 |
| 2001 | 2.51 | 120 |
| 2000 | 3.01 | 95 |
| 1999 | 0.28 | 143 |
| 1998 | 1.24 | 132 |
| 1997 | 1.19 | 150 |
| 1996 | 2.29 | 131 |
| 1995 | 3.76 | 119 |
| 1994 | 1.68 | 138 |
| 1993 | 1.29 | 132 |
| 1992 | 1.02 | 128 |
| 1991 | 2.6 | 120 |
| 1990 | 6.1 | 88 |
| 1989 | 5.72 | 83 |
| 1988 | 6.38 | 74 |
| 1987 | 15.74 | 35 |
| 1986 | 13.22 | 42 |