| 时间 | 值 （%） | 世界排名 |
|---|---|---|
| 2016 | 6.2 | 20 |
| 2015 | 6.5 | 20 |
| 2014 | 10.3 | 1 |
| 2013 | 10.2 | 9 |
| 2012 | 11.1 | 7 |
| 2011 | 14.7 | 4 |
| 2010 | 9.2 | 17 |
| 2009 | 6.1 | 25 |
| 2008 | 14.7 | 3 |
| 2007 | 11.06 | 19 |
| 2006 | 10.97 | 14 |
| 2005 | 13.04 | 9 |
| 2004 | 5 | 103 |
| 2003 | 3.27 | 120 |
| 2002 | 0.26 | 162 |
| 2001 | 4.34 | 64 |
| 2000 | 5.47 | 64 |
| 1999 | 16.5 | 4 |
| 1998 | 7.1 | 29 |
| 1997 | -11.4 | 193 |
| 1996 | 6.7 | 46 |
| 1995 | -7.2 | 178 |
| 1994 | -17.3 | 177 |
| 1993 | 1.5 | 107 |
| 1992 | -14.97 | 172 |
| 1991 | -4.61 | 154 |
| 1990 | 35.38 | 2 |
| 1989 | -4.26 | 156 |
| 1988 | 11.02 | 17 |