| 时间 | 值 （%） | 世界排名 |
|---|---|---|
| 2016 | 4.79 | 15 |
| 2015 | 4.84 | 16 |
| 2014 | 4.92 | 17 |
| 2013 | 5.03 | 18 |
| 2012 | 5.16 | 23 |
| 2011 | 5.29 | 28 |
| 2010 | 5.41 | 30 |
| 2009 | 5.53 | 32 |
| 2008 | 5.65 | 34 |
| 2007 | 5.77 | 40 |
| 2006 | 5.9 | 48 |
| 2005 | 6.03 | 56 |
| 2004 | 6.15 | 60 |
| 2003 | 6.27 | 60 |
| 2002 | 6.41 | 62 |
| 2001 | 6.55 | 67 |
| 2000 | 6.68 | 71 |
| 1999 | 6.83 | 75 |
| 1998 | 6.99 | 79 |
| 1997 | 7.15 | 81 |
| 1996 | 7.3 | 82 |
| 1995 | 7.44 | 89 |
| 1994 | 7.53 | 93 |
| 1993 | 7.62 | 97 |
| 1992 | 7.69 | 101 |
| 1991 | 7.73 | 105 |
| 1990 | 7.76 | 108 |
| 1989 | 7.73 | 110 |
| 1988 | 7.69 | 107 |
| 1987 | 7.65 | 105 |
| 1986 | 7.6 | 105 |