| 时间 | 值 （%） | 世界排名 |
|---|---|---|
| 2016 | 19.1 | 15 |
| 2015 | 23.77 | 14 |
| 2014 | 7.74 | 98 |
| 2013 | 7.57 | 103 |
| 2012 | 7.17 | 102 |
| 2011 | 6.84 | 106 |
| 2010 | 26.12 | 19 |
| 2009 | 13.59 | 66 |
| 2008 | 12.85 | 97 |
| 2007 | 11.47 | 125 |
| 2006 | 2.44 | 159 |
| 2005 | 17.82 | 63 |
| 2004 | 5.43 | 140 |
| 2003 | 38.9 | 15 |
| 2002 | 23.08 | 39 |
| 2001 | 15.4 | 75 |
| 2000 | 20.3 | 48 |
| 1999 | 23.67 | 34 |
| 1998 | 9.24 | 91 |
| 1997 | 20.14 | 59 |
| 1996 | 1.13 | 143 |
| 1995 | 27.11 | 47 |
| 1994 | 31.45 | 50 |
| 1993 | 29.16 | 40 |
| 1992 | 30.47 | 35 |
| 1991 | 11.88 | 82 |
| 1990 | 2.52 | 108 |
| 1989 | 37.61 | 23 |
| 1988 | -10.31 | 121 |
| 1987 | 12.73 | 72 |
| 1986 | 9.2 | 86 |