| 时间 | 值 （%） | 世界排名 |
|---|---|---|
| 2016 | 4.51 | 45 |
| 2015 | 4.37 | 45 |
| 2014 | 4.1 | 42 |
| 2013 | 4.1 | 43 |
| 2012 | 4.1 | 43 |
| 2011 | 4.11 | 39 |
| 2010 | 4.11 | 35 |
| 2009 | 3.51 | 28 |
| 2008 | 3.21 | 32 |
| 2007 | 2.9 | 23 |
| 2006 | 3.65 | 34 |
| 2005 | 4.4 | 39 |
| 2004 | 5.14 | 52 |
| 2003 | 6 | 62 |
| 2002 | 5.92 | 64 |
| 2001 | 7.5 | 90 |
| 2000 | 6.49 | 69 |
| 1999 | 6.14 | 62 |
| 1998 | 8.12 | 95 |
| 1997 | 8.11 | 94 |
| 1996 | 8.1 | 92 |
| 1995 | 4.26 | 41 |
| 1994 | 5.32 | 56 |
| 1993 | 5.31 | 60 |
| 1992 | 5.3 | 59 |
| 1991 | 5.28 | 56 |