| 时间 | 值 （%） | 世界排名 |
|---|---|---|
| 2016 | 5.74 | 26 |
| 2015 | 4.71 | 48 |
| 2014 | 4.67 | 58 |
| 2013 | 4.4 | 76 |
| 2012 | 3.51 | 97 |
| 2011 | 2.75 | 121 |
| 2010 | 1.61 | 157 |
| 2009 | 2.83 | 64 |
| 2008 | 1.7 | 145 |
| 2007 | 4.83 | 120 |
| 2006 | 6.18 | 84 |
| 2005 | 7.67 | 40 |
| 2004 | 7.37 | 49 |
| 2003 | 4.85 | 79 |
| 2002 | 3.22 | 100 |
| 2001 | 1.98 | 130 |
| 2000 | 4.26 | 95 |
| 1999 | 3.66 | 87 |
| 1998 | 2.55 | 136 |
| 1997 | 1.01 | 166 |
| 1996 | 4.85 | 81 |
| 1995 | 4.96 | 71 |
| 1994 | 3.74 | 93 |
| 1993 | 1.76 | 104 |
| 1992 | 7.71 | 30 |
| 1991 | 5.06 | 47 |
| 1990 | 4.46 | 59 |
| 1989 | 4.96 | 55 |
| 1988 | 7.63 | 38 |
| 1987 | 6.45 | 41 |
| 1986 | 5.5 | 47 |