| 时间 | 值 （%） | 世界排名 |
|---|---|---|
| 2015 | 18.81 | 25 |
| 2014 | 15.57 | 31 |
| 2013 | 9.84 | 80 |
| 2012 | 12.61 | 63 |
| 2011 | 18.24 | 37 |
| 2010 | 25.43 | 20 |
| 2009 | 17.72 | 42 |
| 2008 | 19.85 | 51 |
| 2007 | 20.51 | 68 |
| 2006 | 21.5 | 69 |
| 2005 | 34.78 | 18 |
| 2004 | 13.49 | 83 |
| 2003 | 17.97 | 51 |
| 2002 | 25.56 | 35 |
| 2001 | 34.23 | 34 |
| 2000 | 14.8 | 73 |
| 1999 | 18.55 | 54 |
| 1998 | 10.78 | 83 |
| 1997 | 12.85 | 91 |
| 1996 | 8.4 | 110 |
| 1995 | 33.01 | 33 |
| 1994 | 35.35 | 42 |
| 1993 | 39.22 | 25 |
| 1992 | 40.59 | 25 |
| 1991 | 30.08 | 34 |
| 1990 | 41.86 | 22 |
| 1989 | 32.05 | 29 |
| 1988 | 32.83 | 24 |
| 1987 | 32.06 | 28 |
| 1986 | 27.72 | 24 |