| Year | Average |
| 2001 | 3197967 |
| 2002 | 3024705 |
| 2003 | 3222920 |
| 2004 | 3272676 |
| 2005 | 3175657 |
| 2006 | 3361137 |
| 2007 | 3259941 |
| 2008 | 2930669 |
| 2009 | 2733117 |
| 2010 | 2649969 |