| 时间 | 值 （%） | 世界排名 |
|---|---|---|
| 2016 | 1.56 | 115 |
| 2015 | 1.24 | 127 |
| 2014 | 1.05 | 138 |
| 2013 | 1.53 | 113 |
| 2012 | 2.96 | 66 |
| 2011 | 5.12 | 14 |
| 2010 | 7.98 | 2 |
| 2009 | 11.03 | 2 |
| 2008 | 13.59 | 2 |
| 2007 | 14.68 | 2 |
| 2006 | 13.98 | 2 |
| 2005 | 11.83 | 2 |
| 2004 | 9.33 | 2 |
| 2003 | 6.98 | 2 |
| 2002 | 5.81 | 8 |
| 2001 | 5.8 | 8 |
| 2000 | 5.96 | 8 |
| 1999 | 5.69 | 8 |
| 1998 | 5.55 | 11 |
| 1997 | 5.46 | 9 |
| 1996 | 5.09 | 13 |
| 1995 | 4.84 | 16 |
| 1994 | 5.16 | 15 |
| 1993 | 5.44 | 17 |
| 1992 | 5.57 | 17 |
| 1991 | 5.55 | 20 |
| 1990 | 5.58 | 21 |
| 1989 | 5.69 | 20 |
| 1988 | 5.74 | 22 |
| 1987 | 5.66 | 28 |
| 1986 | 5.45 | 35 |