| 时间 | 值 （%） | 世界排名 |
|---|---|---|
| 2016 | 66 | 10 |
| 2015 | 55.8 | 13 |
| 2014 | 48.2 | 16 |
| 2013 | 50.3 | 14 |
| 2012 | 58.9 | 11 |
| 2011 | 81.2 | 9 |
| 2010 | 99 | 8 |
| 2009 | 90.8 | 9 |
| 2008 | 79.6 | 16 |
| 2007 | 160.8 | 9 |
| 2006 | 114.9 | 10 |
| 2005 | 88.3 | 10 |
| 2004 | 88.8 | 8 |
| 2003 | 90.3 | 6 |
| 2002 | 73.7 | 7 |
| 2001 | 63.5 | 13 |
| 2000 | 51.3 | 22 |
| 1999 | 51.1 | 17 |
| 1998 | 38.9 | 17 |
| 1997 | 34.4 | 13 |
| 1996 | 36.1 | 10 |
| 1995 | 26.7 | 12 |
| 1994 | 30.8 | 11 |
| 1993 | 21.4 | 12 |
| 1992 | 12.9 | 12 |
| 1991 | 14 | 12 |
| 1990 | 12.9 | 13 |
| 1989 | 14.5 | 14 |
| 1988 | 17.3 | 10 |
| 1987 | 30.4 | 8 |
| 1986 | 12.4 | 10 |