| 时间 | 值 （%） | 世界排名 |
|---|---|---|
| 2016 | 1.4 | 2 |
| 2015 | 1.28 | 2 |
| 2014 | 1.23 | 2 |
| 2013 | 1.2 | 2 |
| 2012 | 1.2 | 2 |
| 2011 | 1.2 | 2 |
| 2010 | 1.22 | 2 |
| 2009 | 1.27 | 2 |
| 2008 | 1.32 | 2 |
| 2007 | 1.39 | 2 |
| 2006 | 1.47 | 2 |
| 2005 | 1.61 | 2 |
| 2004 | 1.73 | 2 |
| 2003 | 1.87 | 2 |
| 2002 | 2.01 | 2 |
| 2001 | 2.16 | 2 |
| 2000 | 2.32 | 3 |
| 1999 | 2.24 | 3 |
| 1998 | 2.16 | 3 |
| 1997 | 2.09 | 3 |
| 1996 | 2.02 | 3 |
| 1995 | 1.95 | 2 |
| 1994 | 1.95 | 2 |
| 1993 | 1.93 | 2 |
| 1992 | 1.9 | 2 |
| 1991 | 1.86 | 2 |
| 1990 | 1.81 | 2 |
| 1989 | 1.8 | 2 |
| 1988 | 1.8 | 2 |
| 1987 | 1.8 | 2 |
| 1986 | 1.82 | 2 |