| 时间 | 值 （%） | 世界排名 |
|---|---|---|
| 2016 | 51.8 | 186 |
| 2015 | 51.7 | 185 |
| 2014 | 51.6 | 185 |
| 2013 | 51.6 | 182 |
| 2012 | 51.6 | 179 |
| 2011 | 51.6 | 180 |
| 2010 | 51.7 | 180 |
| 2009 | 51.7 | 180 |
| 2008 | 51.7 | 179 |
| 2007 | 51.6 | 179 |
| 2006 | 51.7 | 178 |
| 2005 | 51.8 | 176 |
| 2004 | 51.8 | 175 |
| 2003 | 51.9 | 175 |
| 2002 | 52 | 173 |
| 2001 | 52.1 | 171 |
| 2000 | 52.1 | 168 |
| 1999 | 52 | 166 |
| 1998 | 51.8 | 167 |
| 1997 | 51.7 | 167 |
| 1996 | 51.7 | 166 |
| 1995 | 51.7 | 165 |
| 1994 | 51.5 | 166 |
| 1993 | 51.3 | 166 |
| 1992 | 51.3 | 161 |
| 1991 | 51.2 | 163 |
| 1990 | 51.2 | 161 |
| 1989 | 51.1 | 158 |
| 1988 | 51 | 157 |
| 1987 | 50.9 | 157 |
| 1986 | 50.9 | 158 |