| 时间 | 值 （%） | 世界排名 |
|---|---|---|
| 2016 | 8.74 | 12 |
| 2015 | 9.03 | 17 |
| 2014 | 6.33 | 33 |
| 2013 | 6.2 | 39 |
| 2012 | 5.4 | 64 |
| 2011 | 6.64 | 61 |
| 2010 | 5.04 | 64 |
| 2009 | 4.89 | 60 |
| 2008 | 5.66 | 127 |
| 2007 | 3.64 | 115 |
| 2006 | 4.18 | 95 |
| 2005 | 6.87 | 62 |
| 2004 | 6.6 | 56 |
| 2003 | 14.72 | 20 |
| 2002 | 8.45 | 40 |
| 2001 | 6.84 | 49 |
| 2000 | 7.04 | 47 |
| 1999 | 4.86 | 64 |
| 1998 | 3.2 | 102 |
| 1997 | 6.93 | 72 |
| 1996 | 15.76 | 48 |
| 1995 | 66.01 | 17 |
| 1994 | 2075.89 | 4 |
| 1993 | 1927.98 | 3 |
| 1992 | 951.65 | 2 |
| 1991 | 432.78 | 3 |
| 1990 | 2947.73 | 3 |
| 1989 | 1430.72 | 4 |
| 1988 | 629.11 | 3 |
| 1987 | 228.34 | 2 |
| 1986 | 147.14 | 4 |