| 时间 | 值 （%） | 世界排名 |
|---|---|---|
| 2016 | 15.7 | 6 |
| 2015 | 9.02 | 18 |
| 2014 | 8.06 | 19 |
| 2013 | 8.48 | 19 |
| 2012 | 12.22 | 16 |
| 2011 | 10.84 | 25 |
| 2010 | 13.72 | 6 |
| 2009 | 11.54 | 16 |
| 2008 | 11.58 | 55 |
| 2007 | 5.38 | 87 |
| 2006 | 8.24 | 45 |
| 2005 | 17.86 | 8 |
| 2004 | 15 | 10 |
| 2003 | 14.03 | 23 |
| 2002 | 12.88 | 23 |
| 2001 | 18.87 | 16 |
| 2000 | 6.93 | 48 |
| 1999 | 6.62 | 50 |
| 1998 | 10 | 46 |
| 1997 | 8.53 | 56 |
| 1996 | 29.27 | 23 |
| 1995 | 72.84 | 15 |
| 1994 | 57.03 | 22 |
| 1993 | 57.17 | 21 |
| 1992 | 44.59 | 21 |
| 1991 | 13.01 | 56 |
| 1990 | 7.36 | 76 |
| 1989 | 50.47 | 17 |
| 1988 | 54.51 | 14 |
| 1987 | 11.29 | 44 |
| 1986 | 5.72 | 68 |