| 时间 | 值 （%） | 世界排名 |
|---|---|---|
| 2016 | 3.55 | 40 |
| 2015 | 2.17 | 77 |
| 2014 | 2.03 | 98 |
| 2013 | 2.13 | 106 |
| 2012 | 0.71 | 170 |
| 2011 | 1.3 | 168 |
| 2010 | 2.4 | 115 |
| 2009 | 2.17 | 106 |
| 2008 | 3.77 | 156 |
| 2007 | 0.73 | 170 |
| 2006 | 2.33 | 139 |
| 2005 | 1.52 | 156 |
| 2004 | 0.47 | 154 |
| 2003 | 2.48 | 101 |
| 2002 | 1.29 | 137 |
| 2001 | 3.02 | 107 |
| 2000 | 3.09 | 93 |
| 1999 | 2.33 | 97 |
| 1998 | 2.26 | 114 |
| 1997 | 2.58 | 118 |
| 1996 | 1.26 | 148 |
| 1995 | 2.46 | 133 |
| 1994 | 1.4 | 143 |
| 1993 | 2.27 | 120 |
| 1992 | 2.34 | 117 |
| 1991 | 3.42 | 109 |
| 1990 | 4.11 | 100 |
| 1989 | 4.56 | 93 |
| 1988 | 6.7 | 72 |
| 1987 | 8.73 | 53 |
| 1986 | 7.19 | 61 |