| 时间 | 值 （%） | 世界排名 |
|---|---|---|
| 2016 | 81.05 | 7 |
| 2015 | 81.1 | 7 |
| 2014 | 81.13 | 7 |
| 2013 | 81.12 | 7 |
| 2012 | 81.09 | 7 |
| 2011 | 81.08 | 9 |
| 2010 | 81.03 | 8 |
| 2009 | 80.93 | 7 |
| 2008 | 80.82 | 7 |
| 2007 | 80.66 | 8 |
| 2006 | 80.5 | 8 |
| 2005 | 79.8 | 8 |
| 2004 | 79.08 | 8 |
| 2003 | 78.34 | 10 |
| 2002 | 77.57 | 10 |
| 2001 | 76.79 | 11 |
| 2000 | 75.98 | 12 |
| 1999 | 75.14 | 13 |
| 1998 | 74.28 | 14 |
| 1997 | 73.39 | 16 |
| 1996 | 72.47 | 19 |
| 1995 | 71.52 | 21 |
| 1994 | 70.56 | 23 |
| 1993 | 69.56 | 25 |
| 1992 | 68.53 | 29 |
| 1991 | 67.46 | 30 |
| 1990 | 66.35 | 32 |