| year | East (173) | North (202) | Southeast (74) | West (610) |
|---|---|---|---|---|
| 1992 | 1.7 | 0.5 | 2.7 | 3.6 |
| 1993 | 1.5 | 0.5 | 2.0 | 3.6 |
| 1994 | 1.5 | 0.5 | 2.3 | 3.5 |
| 1995 | 1.5 | 0.5 | 2.5 | 3.4 |
| 1996 | 1.5 | 0.6 | 3.1 | 3.5 |
| 1997 | 1.5 | 0.5 | 2.7 | 3.4 |
| 1998 | 1.7 | 0.5 | 2.1 | 3.6 |
| 1999 | 1.5 | 0.4 | 2.0 | 3.4 |
| 2000 | 1.5 | 0.5 | 2.2 | 3.3 |
| 2001 | 1.6 | 0.5 | 2.0 | 3.2 |
| 2002 | 1.5 | 0.4 | 1.7 | 3.1 |
| 2003 | 1.4 | 0.5 | 2.0 | 3.0 |
| 2004 | 1.6 | 0.5 | 1.9 | 3.3 |
| 2005 | 1.5 | 0.4 | 1.8 | 3.1 |
| 2006 | 1.5 | 0.5 | 2.1 | 3.3 |
| 2007 | 1.8 | 0.4 | 1.8 | 3.1 |
| 2008 | 1.6 | 0.4 | 1.5 | 3.0 |
| 2009 | 1.5 | 0.3 | 1.3 | 2.9 |
| 2010 | 1.5 | 0.4 | 1.5 | 3.0 |
| 2011 | 1.6 | 0.4 | 1.6 | 2.8 |
| 2012 | 1.7 | 0.4 | 1.6 | 2.8 |