| 时间 | 值 （%） | 世界排名 |
|---|---|---|
| 2016 | 4.11 | 24 |
| 2015 | 1.12 | 147 |
| 2014 | 5.71 | 49 |
| 2013 | 4.78 | 53 |
| 2012 | 10.16 | 26 |
| 2011 | 4.01 | 81 |
| 2010 | 3.55 | 82 |
| 2009 | 2.29 | 111 |
| 2008 | 2.99 | 122 |
| 2007 | 2.51 | 139 |
| 2006 | 6.33 | 70 |
| 2005 | 2.24 | 114 |
| 2004 | 1.32 | 134 |
| 2003 | 6.27 | 35 |
| 2002 | 0.44 | 152 |
| 2001 | 5.03 | 42 |
| 2000 | 6.16 | 37 |
| 1999 | 0.92 | 122 |
| 1998 | 2.42 | 92 |
| 1997 | 2.01 | 93 |
| 1996 | 1.1 | 103 |
| 1995 | 0.58 | 117 |
| 1994 | 1.27 | 77 |
| 1993 | 1.61 | 57 |
| 1992 | 1.74 | 45 |
| 1991 | 2.74 | 31 |
| 1990 | 3.32 | 22 |
| 1989 | 2.87 | 27 |
| 1988 | 1.64 | 35 |
| 1987 | 0.97 | 49 |
| 1986 | 0.61 | 58 |