Period | Average | Standard Deviation |
Jan 1997-Sept 2001 | 9.94 | 4.3 |
Oct 2001-July 2005 | 5.1 | 1.58 |
Aug 2005-April 2009 | 8.24 | 2.52 |
May 2009-Dec 2010 | 8.9 | 3.0 |
Overall Period | ||
Jan 1997-Dec 2010 | 8.1 | 3.7 |