| 时间 | 值 （%） | 世界排名 |
|---|---|---|
| 2016 | 81.05 | 9 |
| 2015 | 80.9 | 12 |
| 2014 | 80.74 | 13 |
| 2013 | 80.56 | 13 |
| 2012 | 80.36 | 13 |
| 2011 | 80.14 | 13 |
| 2010 | 79.92 | 15 |
| 2009 | 79.7 | 16 |
| 2008 | 79.48 | 16 |
| 2007 | 79.25 | 15 |
| 2006 | 79.02 | 16 |
| 2005 | 78.78 | 16 |
| 2004 | 78.54 | 18 |
| 2003 | 78.3 | 19 |
| 2002 | 78.06 | 21 |
| 2001 | 77.93 | 22 |
| 2000 | 78.02 | 22 |
| 1999 | 78.11 | 23 |
| 1998 | 78.2 | 24 |
| 1997 | 78.3 | 24 |
| 1996 | 78.38 | 25 |
| 1995 | 78.47 | 25 |
| 1994 | 78.56 | 25 |
| 1993 | 78.65 | 25 |
| 1992 | 78.74 | 27 |
| 1991 | 78.8 | 27 |
| 1990 | 78.8 | 29 |
| 1989 | 78.8 | 29 |
| 1988 | 78.8 | 29 |
| 1987 | 78.8 | 30 |
| 1986 | 78.8 | 30 |