| 时间 | 值 （%） | 世界排名 |
|---|---|---|
| 2016 | 77.69 | 68 |
| 2015 | 77.55 | 67 |
| 2014 | 77.27 | 71 |
| 2013 | 76.91 | 72 |
| 2012 | 76.48 | 78 |
| 2011 | 76.07 | 83 |
| 2010 | 75.73 | 81 |
| 2009 | 75.46 | 83 |
| 2008 | 75.23 | 86 |
| 2007 | 75.06 | 90 |
| 2006 | 74.91 | 93 |
| 2005 | 74.79 | 91 |
| 2004 | 74.69 | 89 |
| 2003 | 74.58 | 89 |
| 2002 | 74.46 | 93 |
| 2001 | 74.3 | 96 |
| 2000 | 73.95 | 103 |
| 1999 | 73.49 | 113 |
| 1998 | 72.97 | 114 |
| 1997 | 72.77 | 118 |
| 1996 | 73.38 | 116 |
| 1995 | 73.73 | 114 |
| 1994 | 74.03 | 113 |
| 1993 | 74.56 | 107 |
| 1992 | 74.78 | 108 |
| 1991 | 74.84 | 113 |
| 1990 | 74.84 | 115 |