| 时间 | 值 （%） | 世界排名 |
|---|---|---|
| 2016 | 12.29 | 56 |
| 2015 | 11.69 | 56 |
| 2014 | 11.06 | 56 |
| 2013 | 10.46 | 59 |
| 2012 | 9.9 | 60 |
| 2011 | 9.42 | 61 |
| 2010 | 9.02 | 62 |
| 2009 | 8.89 | 61 |
| 2008 | 8.79 | 61 |
| 2007 | 8.65 | 60 |
| 2006 | 8.46 | 60 |
| 2005 | 8.23 | 60 |
| 2004 | 8.01 | 62 |
| 2003 | 7.85 | 62 |
| 2002 | 7.7 | 62 |
| 2001 | 7.53 | 62 |
| 2000 | 7.35 | 64 |
| 1999 | 7.1 | 64 |
| 1998 | 6.87 | 66 |
| 1997 | 6.67 | 68 |
| 1996 | 6.49 | 69 |
| 1995 | 6.35 | 69 |
| 1994 | 6.17 | 69 |
| 1993 | 6.01 | 69 |
| 1992 | 5.86 | 70 |
| 1991 | 5.73 | 71 |
| 1990 | 5.6 | 72 |
| 1989 | 5.53 | 70 |
| 1988 | 5.47 | 70 |
| 1987 | 5.41 | 70 |
| 1986 | 5.34 | 71 |