| 时间 | 值 （%） | 世界排名 |
|---|---|---|
| 2015 | 10.1 | 15 |
| 2014 | 7.81 | 21 |
| 2013 | 6.98 | 32 |
| 2012 | 6.58 | 47 |
| 2011 | 6.43 | 64 |
| 2010 | 8.5 | 24 |
| 2009 | 13.4 | 9 |
| 2008 | 12.45 | 47 |
| 2007 | 10.66 | 22 |
| 2006 | 9.02 | 37 |
| 2005 | 18.32 | 7 |
| 2004 | 17.97 | 8 |
| 2003 | 21.4 | 12 |
| 2002 | 22.23 | 11 |
| 2001 | 21.39 | 14 |
| 2000 | 26.03 | 13 |
| 1999 | 26.79 | 16 |
| 1998 | 24.46 | 17 |
| 1997 | 24.42 | 18 |
| 1996 | 43.07 | 15 |
| 1995 | 34.93 | 29 |
| 1994 | 54.6 | 23 |
| 1993 | 183.31 | 13 |
| 1992 | 165.71 | 7 |
| 1991 | 97.64 | 12 |
| 1990 | 107.02 | 8 |
| 1989 | 123.4 | 6 |
| 1988 | 51 | 15 |
| 1987 | 47.05 | 12 |
| 1986 | 55.83 | 11 |