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