| 时间 | 值 （%） | 世界排名 |
|---|---|---|
| 2016 | 4.95 | 19 |
| 2015 | 8.44 | 31 |
| 2014 | 9.2 | 27 |
| 2013 | 7.58 | 29 |
| 2012 | 11.44 | 22 |
| 2011 | 9.66 | 31 |
| 2010 | 7.39 | 44 |
| 2009 | 8.1 | 41 |
| 2008 | 10.37 | 32 |
| 2007 | 7.81 | 65 |
| 2006 | 4.95 | 82 |
| 2005 | 6.12 | 49 |
| 2004 | 6.9 | 41 |
| 2003 | 5.37 | 43 |
| 2002 | 3.66 | 68 |
| 2001 | 5.92 | 34 |
| 2000 | 6.24 | 35 |
| 1999 | 11.65 | 16 |
| 1998 | 5.67 | 37 |
| 1997 | 6.21 | 24 |
| 1996 | 6.17 | 21 |
| 1995 | 4.03 | 36 |
| 1994 | 4.53 | 19 |
| 1993 | 2.1 | 42 |
| 1992 | 2.04 | 40 |
| 1991 | 2.17 | 39 |
| 1990 | 2 | 40 |
| 1989 | 4.29 | 16 |
| 1988 | 3.72 | 18 |
| 1987 | 4 | 13 |
| 1986 | 1.67 | 26 |