| 时间 | 值 （%） | 世界排名 |
|---|---|---|
| 2016 | 32.8 | 23 |
| 2015 | 33 | 21 |
| 2014 | 29.7 | 29 |
| 2013 | 22.5 | 33 |
| 2012 | 22.3 | 32 |
| 2011 | 45.5 | 28 |
| 2010 | 38.8 | 30 |
| 2009 | 45.2 | 31 |
| 2008 | 128.6 | 18 |
| 2007 | 54.6 | 25 |
| 2006 | 43 | 26 |
| 2005 | 34.3 | 27 |
| 2004 | 29.5 | 31 |
| 2003 | 21.3 | 35 |
| 2002 | 19.4 | 33 |
| 2001 | 29 | 32 |
| 2000 | 32.3 | 33 |
| 1999 | 35.8 | 27 |
| 1998 | 694.4 | 1 |
| 1997 | 32.8 | 31 |
| 1996 | 32.4 | 24 |
| 1995 | 42.5 | 14 |
| 1994 | 30.4 | 21 |
| 1993 | 25.1 | 22 |
| 1992 | 24.1 | 19 |
| 1991 | 31.7 | 12 |
| 1990 | 219.1 | 2 |
| 1989 | 108 | 2 |
| 1988 | 19.8 | 16 |
| 1987 | 17.4 | 22 |
| 1986 | 18 | 14 |