| 时间 | 值 （人/平方公里） | 世界排名 |
|---|---|---|
| 2016 | 49.6 | 145 |
| 2015 | 48.3 | 147 |
| 2014 | 47 | 144 |
| 2013 | 45.8 | 147 |
| 2012 | 44.6 | 148 |
| 2011 | 43.4 | 149 |
| 2010 | 42.2 | 149 |
| 2009 | 41.1 | 150 |
| 2008 | 40 | 151 |
| 2007 | 38.9 | 151 |
| 2006 | 37.9 | 151 |
| 2005 | 36.9 | 151 |
| 2004 | 35.9 | 152 |
| 2003 | 34.9 | 152 |
| 2002 | 34 | 152 |
| 2001 | 33.2 | 152 |
| 2000 | 32.3 | 153 |
| 1999 | 31.5 | 151 |
| 1998 | 30.7 | 152 |
| 1997 | 30 | 151 |
| 1996 | 29.2 | 152 |
| 1995 | 28.5 | 152 |
| 1994 | 27.7 | 151 |
| 1993 | 27 | 150 |
| 1992 | 26.3 | 150 |
| 1991 | 25.5 | 151 |
| 1990 | 24.8 | 147 |
| 1989 | 24.1 | 145 |
| 1988 | 23.3 | 144 |
| 1987 | 22.6 | 145 |
| 1986 | 21.9 | 145 |