| 时间 | 值 （%） | 世界排名 |
|---|---|---|
| 2016 | 59.5 | 147 |
| 2015 | 59.2 | 147 |
| 2014 | 59 | 146 |
| 2013 | 58.6 | 147 |
| 2012 | 58.3 | 147 |
| 2011 | 57.9 | 147 |
| 2010 | 57.5 | 147 |
| 2009 | 57 | 147 |
| 2008 | 56.5 | 147 |
| 2007 | 56 | 150 |
| 2006 | 55.4 | 153 |
| 2005 | 54.8 | 155 |
| 2004 | 54.4 | 157 |
| 2003 | 54 | 159 |
| 2002 | 53.5 | 160 |
| 2001 | 53.1 | 161 |
| 2000 | 52.6 | 162 |
| 1999 | 51.9 | 168 |
| 1998 | 51.3 | 173 |
| 1997 | 50.8 | 176 |
| 1996 | 50.4 | 180 |
| 1995 | 50 | 182 |
| 1994 | 49.7 | 184 |
| 1993 | 49.5 | 185 |
| 1992 | 49.3 | 185 |
| 1991 | 49.3 | 184 |
| 1990 | 49.4 | 185 |
| 1989 | 49.1 | 187 |
| 1988 | 48.8 | 188 |
| 1987 | 48.7 | 188 |
| 1986 | 48.5 | 188 |