| 时间 | 值 （%） | 世界排名 |
|---|---|---|
| 2016 | 3.85 | 37 |
| 2015 | 3.39 | 29 |
| 2014 | 3.31 | 28 |
| 2013 | 3.59 | 35 |
| 2012 | 5 | 53 |
| 2011 | 4.7 | 51 |
| 2010 | 5.93 | 61 |
| 2009 | 5.28 | 50 |
| 2008 | 4.63 | 54 |
| 2007 | 5.54 | 66 |
| 2006 | 6.27 | 70 |
| 2005 | 7.95 | 100 |
| 2004 | 8.3 | 98 |
| 2003 | 10.5 | 122 |
| 2002 | 10.39 | 122 |
| 2001 | 10.8 | 126 |
| 2000 | 12.1 | 135 |
| 1999 | 13.12 | 140 |
| 1998 | 14.21 | 150 |
| 1997 | 15.01 | 156 |
| 1996 | 16.25 | 159 |
| 1995 | 17.22 | 161 |
| 1994 | 18.44 | 164 |
| 1993 | 19.81 | 171 |
| 1992 | 19.66 | 171 |
| 1991 | 18.52 | 166 |