The click throughs obtained for Eltronix Inc during an eight-week period are provided in the table below. Eltronix ran a branded keyword search campaign in the first four weeks at a CPC of $0.15. Eltronix did not sponsor branded keywords in the second four-week period. Assume no systematic difference exists between the two four-week periods. The conversion rate was 3.00 % and the margin per order was $ 15.00 during the eight weeks.

The data:

week	sponsored click-throughs	organic click-throughs
1	31,002	198,566
2	29,005	199,025
3	27,852	193,255
4	24,056	201,255
5		220,040
6		218,508
7		210,004
8		218,540

(please show excel pivot chart and formulae that summarize differences in click-throughs between the two 4-week periods)

Compute the ROI% that should be attributed to the campaign.