Did you check the reports in the Sales Information System - like MC+E?
They can provide some starting point for such analysis.
If the company uses BW, then check what reports they have defined there.
If you need to determine the appropriate credit limits for customers in your organization, the information on billed quantity within a specific time frame is just a part of the whole picture. There are some useful FI reports like S_ALR_87012177 - Customer payment history, S_ALR_87012619 - Transaction figures: Account Balance; S_ALR_87012167 - Accounts Receivable Information System etc.
Your colleagues from the Finance department, who deal with AR can show you what they currently use for analytical purposes.