For a mainframe computer, a preventive maintenance (PM) inspection and repair cycle costs a total of $2,000 on the average. If the computer breaks down, an average cost of $5,000 is incurred. The historical breakdown pattern for the computer is the following:

Months between PM	Average number of breakdowns between PM
1	0.2
2	0.6
3	1.8
4	3.6
5	7.0

Recommend how often preventive maintenance should be performed based on the total annual cost considering the breakdown cost and the PM cost.