Running Conversion on last 6 weeks of data

Hi there,

See the below chart. I need a formula starting in week 7 (column H), and then going forward that I can use to convert the number of deals sold based on the number of appts had over a 6 week period. So for example in week 7, take the previous 6 weeks of date (so total appts had for week 1-6 was 15, and total deals sold was 2, so 2/15 = 13.3% conversion rate. Then in the next column take the total appts had from week 2-7, and so on. Is this possible? Thanks!!