can I reduce the number of queries?

Thanks for your previous post. I've run into another hurdle, and would
greatly appreciate any help you may be able to offer. I have revenue
data sorted by month and years for a number of distinctly labeled
stores (imagine a Center ID). I would like to find the percentage of
"gainers" (stores whose monthly revenues exceed the previous month's
revenues) out of the all the stores. I know how to determine this by
using an individual queries to sort out each store's revenue by year
and month, and then use another query to classify gainers v. decliners,
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and then (Fnally!) calculate the percentages. Is there an easier way to
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do this than to run around 50 queries (one for each month for 4 years)?
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Thanks.
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Jonathan
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