| 时间 | 值 （%） | 世界排名 |
|---|---|---|
| 2016 | 3.57 | 40 |
| 2015 | 4.5 | 15 |
| 2014 | 5.46 | 6 |
| 2013 | 6.58 | 3 |
| 2012 | 7.9 | 1 |
| 2011 | 9.4 | 1 |
| 2010 | 11.41 | 1 |
| 2009 | 13.75 | 1 |
| 2008 | 15.76 | 1 |
| 2007 | 16.61 | 1 |
| 2006 | 15.86 | 1 |
| 2005 | 13.43 | 1 |
| 2004 | 9.96 | 1 |
| 2003 | 6.62 | 5 |
| 2002 | 4.75 | 21 |
| 2001 | 4.27 | 27 |
| 2000 | 4.14 | 32 |
| 1999 | 3.62 | 54 |
| 1998 | 3.16 | 65 |
| 1997 | 2.65 | 83 |
| 1996 | 2.08 | 106 |
| 1995 | 1.65 | 118 |
| 1994 | 1.53 | 127 |
| 1993 | 1.68 | 127 |
| 1992 | 2.14 | 114 |
| 1991 | 2.83 | 92 |
| 1990 | 3.69 | 71 |
| 1989 | 4.62 | 46 |
| 1988 | 5.63 | 25 |
| 1987 | 6.68 | 14 |
| 1986 | 7.32 | 12 |