Multi-batch Expectations are on our roadmap, but are not implemented yet. Once they exist, it will be possible to express tests like this one: if you have a table of invoices, you can test if the number of invoices today was within x% of the mean count of the last 10 days.
Your case might be possible without waiting for multi-batch. If you are comparing two tables, check out the write-up of a workflow that does it: