| 时间 | 值 （%） | 世界排名 |
|---|---|---|
| 2016 | 57.2 | 153 |
| 2015 | 56.9 | 154 |
| 2014 | 56.6 | 154 |
| 2013 | 56.2 | 155 |
| 2012 | 55.8 | 155 |
| 2011 | 55.3 | 157 |
| 2010 | 54.9 | 159 |
| 2009 | 54.3 | 162 |
| 2008 | 53.7 | 164 |
| 2007 | 53.1 | 169 |
| 2006 | 52.5 | 174 |
| 2005 | 51.9 | 175 |
| 2004 | 51.4 | 176 |
| 2003 | 51 | 180 |
| 2002 | 50.6 | 181 |
| 2001 | 50.2 | 183 |
| 2000 | 49.9 | 187 |
| 1999 | 49.6 | 187 |
| 1998 | 49.4 | 189 |
| 1997 | 49.3 | 190 |
| 1996 | 49.2 | 190 |
| 1995 | 49.3 | 189 |
| 1994 | 49.3 | 189 |
| 1993 | 49.3 | 187 |
| 1992 | 49.3 | 186 |
| 1991 | 49.3 | 185 |
| 1990 | 49.3 | 187 |