It's not currently possible but the next version will have the customer database as a separate entity so you will be able to connect to it using any third party reporting software such as Microsoft Access. I've been meaning to add some simple reporting functionality but haven't done it as yet.
If you know C#, you can connect to the backend data layer and do some simple reporting via code but I don't have any documentation for it at this stage.
Pseudo code would be something along these lines...
for each customer in tandemvids.customers
if (customer.SkydiveDate >= date_start && customer.SkydiveDate <= date_end && customer.DVD) dvd_count++;
Another simple way to do it would be to select all customers on the search tab (CTRL + A) and then copy (CTRL + C) and paste into Microsoft Excel. At the end of the true/false columns such as DVD, you add count formulas shown below. It's pretty simple maths from there to get the percentages. On the search tab, you can add or remove columns to get the desired results. Let me know if you need a hand.