| 时间 | 值 （%） | 世界排名 |
|---|---|---|
| 2016 | 13.44 | 51 |
| 2015 | 12.97 | 51 |
| 2014 | 12.48 | 52 |
| 2013 | 12 | 53 |
| 2012 | 11.54 | 53 |
| 2011 | 11.1 | 53 |
| 2010 | 10.71 | 54 |
| 2009 | 10.3 | 55 |
| 2008 | 9.93 | 57 |
| 2007 | 9.57 | 57 |
| 2006 | 9.22 | 57 |
| 2005 | 8.86 | 57 |
| 2004 | 8.53 | 57 |
| 2003 | 8.19 | 57 |
| 2002 | 7.84 | 59 |
| 2001 | 7.51 | 64 |
| 2000 | 7.18 | 65 |
| 1999 | 6.9 | 67 |
| 1998 | 6.63 | 70 |
| 1997 | 6.38 | 71 |
| 1996 | 6.16 | 72 |
| 1995 | 5.98 | 73 |
| 1994 | 5.8 | 75 |
| 1993 | 5.66 | 75 |
| 1992 | 5.54 | 75 |
| 1991 | 5.4 | 75 |
| 1990 | 5.23 | 75 |
| 1989 | 5.1 | 74 |
| 1988 | 4.94 | 75 |
| 1987 | 4.77 | 75 |
| 1986 | 4.61 | 77 |