| 时间 | 值 （%） | 世界排名 |
|---|---|---|
| 2015 | 6.17 | 50 |
| 2014 | 4.2 | 64 |
| 2013 | 8.86 | 22 |
| 2012 | 3.94 | 75 |
| 2011 | 5.48 | 62 |
| 2010 | 7.84 | 40 |
| 2009 | 13.3 | 14 |
| 2008 | 16.33 | 16 |
| 2007 | 20.64 | 15 |
| 2006 | 12.85 | 31 |
| 2005 | 10.09 | 24 |
| 2004 | 10.85 | 17 |
| 2003 | 15.09 | 11 |
| 2002 | 10.08 | 13 |
| 2001 | 11.29 | 13 |
| 2000 | 7.19 | 31 |
| 1999 | 8.62 | 26 |
| 1998 | 10.92 | 13 |
| 1997 | 8.54 | 16 |
| 1996 | 4.62 | 30 |
| 1995 | 5.84 | 19 |
| 1994 | 5.94 | 14 |
| 1993 | 6.54 | 14 |
| 1992 | 7.28 | 7 |
| 1991 | 5.08 | 14 |
| 1990 | 4.63 | 16 |
| 1989 | 3.92 | 20 |
| 1988 | 6.34 | 9 |
| 1987 | 6.85 | 8 |
| 1986 | 2.39 | 19 |