Write a customer retention report in MS Access 2010

This project is to take a single table of data (Invoice lines) and produce a report. We are trying to see how many customer places repeat orders with ourselves. We would like to enter a start date for the report such as 1st January 2010 I would like to take all customers with ordertype "Mail" that have placed an order in a calendar month this will provide a list of customers that placed an order. We can provide a count of orders from these customers Current Month Count of Customers 94 Value of Orders 8455 Percentage of customers retained 100% Next we look at how many customers placed orders in 3 monthly periods 1st 3 Months Count of Customers 85 Value of Orders 7400 Percentage of customers retained (85/94*100) = 90.4% 2nd 3 Months Count of Customers 75 Value of Orders 6700 Percentage of customers retained (75/94*100) = 79.8% this format continues for eight 3 month periods though some data will not be available for later periods. If at all possible where a period is not complete it should be left blank. Please see attached XLSX spreadsheet for the format of the report.