| 时间 | 值 （%） | 世界排名 |
|---|---|---|
| 2016 | 2.63 | 67 |
| 2015 | 2.62 | 73 |
| 2014 | 2.59 | 72 |
| 2013 | 2.55 | 73 |
| 2012 | 2.48 | 78 |
| 2011 | 2.38 | 82 |
| 2010 | 2.27 | 85 |
| 2009 | 2.18 | 93 |
| 2008 | 2.1 | 94 |
| 2007 | 2.11 | 92 |
| 2006 | 2.15 | 95 |
| 2005 | 2.19 | 94 |
| 2004 | 2.24 | 89 |
| 2003 | 2.33 | 87 |
| 2002 | 2.48 | 84 |
| 2001 | 2.66 | 81 |
| 2000 | 2.86 | 70 |
| 1999 | 3.06 | 67 |
| 1998 | 4.26 | 25 |
| 1997 | 4.94 | 16 |
| 1996 | 5.15 | 12 |
| 1995 | 5.36 | 10 |
| 1994 | 5.56 | 12 |
| 1993 | 5.69 | 14 |
| 1992 | 5.7 | 15 |
| 1991 | 5.61 | 17 |
| 1990 | 5.4 | 25 |
| 1989 | 5.16 | 30 |
| 1988 | 5.06 | 40 |
| 1987 | 5.14 | 42 |
| 1986 | 5.35 | 36 |