Volatility is measurement of the change in price over a given period. It is often expressed as a percentage and computed as the annualized standard deviation of the percentage change in daily price.

	Jan	Feb	Mar	Apr	May	Jun	Jul	Aug	Sep	Oct	Nov	Dec	Yearly Average
1988					1.9	5.6	3.0	3.4	4.4	3.3	3.8	5.1	3.8
1989	3.5	3.2	4.2	5.5	6.0	5.2	3.8	5.6	3.5	3.7	3.6	3.2	4.3
1990	3.3	4.8	3.8	2.8	4.8	3.8	3.3	5.2	2.7	3.3	2.8	4.2	3.7
1991	3.9	2.9	4.2	3.1	2.4	2.7	2.3	4.3	1.9	3.4	2.3	3.2	3.0
1992	4.3	3.9	4.6	4.4	4.7	3.2	4.8	4.6	4.9	5.8	4.5	2.9	4.4
1993	3.9	5.0	4.9	3.0	2.7	3.6	3.3	2.4	4.3	3.0	3.9	2.8	3.6
1994	4.1	3.6	4.0	7.0	6.6	4.7	5.6	4.4	3.7	3.3	4.6	3.9	4.6
1995	4.0	5.0	3.9	2.4	4.2	6.7	4.6	3.7	3.5	2.1	2.6	3.2	3.8
1996	3.5	5.0	7.4	5.2	4.1	4.4	5.5	4.4	3.6	3.5	1.9	3.7	4.3
1997	3.2	3.4	2.6	3.4	2.7	2.7	2.4	3.7	3.3	4.1	1.6	2.7	3.0
1998	4.8	2.7	2.3	3.6	2.4	2.5	1.3	1.8	4.9	6.8	3.7	4.7	3.5
1999	3.5	3.5	2.9	3.9	4.6	4.3	3.4	4.6	4.1	3.7	2.5	3.1	3.7
2000	3.9	4.9	2.8	5.1	3.7	2.9	3.4	2.4	1.6	2.4	2.7	2.9	3.2
2001	5.6	3.7	4.1	5.6	4.5	3.6	2.8	3.3	5.8	3.1	7.8	6.8	4.7
2002	4.6	3.6	5.1	2.8	4.5	4.6	5.7	6.3	5.0	6.6	5.5	3.2	4.8
2003	3.9	3.4	5.0	3.8	3.3	5.4	5.1	6.5	5.4	6.1	5.2	5.1	4.9
2004	5.4	3.6	4.6	5.3	5.2	4.8	4.2	4.2	7.4	2.6	3.7	3.1	4.5
2005	2.4	3.2	3.3	3.1	3.4	3.1	2.7	3.2	2.2	2.1	3.2	2.8	2.9
2006	2.3	1.7	2.9	2.6	2.1	3.0	2.6	2.0	2.3	2.9	3.1	2.6	2.5
2007	2.0	2.9	2.6	2.5	1.6	3.0	4.5	4.8	4.6	3.7	4.8		3.4
Mean	3.8	3.7	3.9	4.0	3.8	4.0	3.7	4.0	4.0	3.8	3.7	3.6	3.8
High	5.6	5.0	7.4	7.0	6.6	6.7	5.7	6.5	7.4	6.8	7.8	6.8	7.8
Low	2.4	1.7	2.3	2.4	1.9	2.5	1.3	1.8	1.6	2.1	1.6	2.6	1.3