| 时间 | 值 （%） | 世界排名 |
|---|---|---|
| 2015 | 28.8 | 38 |
| 2014 | 32.86 | 36 |
| 2013 | 32.53 | 44 |
| 2012 | 35.44 | 36 |
| 2011 | 35.41 | 37 |
| 2010 | 38.38 | 35 |
| 2009 | 35.7 | 37 |
| 2008 | 40.45 | 28 |
| 2007 | 41.92 | 31 |
| 2006 | 39.63 | 32 |
| 2005 | 39.36 | 30 |
| 2004 | 37.34 | 30 |
| 2003 | 35.68 | 28 |
| 2002 | 38.25 | 26 |
| 2001 | 35.8 | 27 |
| 2000 | 39.73 | 23 |
| 1999 | 41.72 | 24 |
| 1998 | 45.61 | 17 |
| 1997 | 45.18 | 16 |
| 1996 | 49.71 | 12 |
| 1995 | 49.41 | 12 |
| 1994 | 47.37 | 18 |
| 1993 | 52.1 | 11 |
| 1992 | 52.23 | 9 |
| 1991 | 56.94 | 6 |
| 1990 | 65.26 | 5 |
| 1989 | 54.55 | 6 |
| 1988 | 43.99 | 11 |
| 1987 | 38.34 | 18 |
| 1986 | 34.51 | 19 |