Repeat Ticketbuyers for Group Sales and Average # of Tickets per Group Sale

Hi All 

I've been asked to find the information below for each fiscal year individually going back to FY18 (skipping FY21 because of Pandemic reasons): 

• # of Repeat Groups per season
• Average # of tickets per group order

Things to note: 

• Groups are 10+ tickets with specific price types and/or through a specific "Groups" mode of sale

Frankly, I'm not even sure where to start on either of these so I appreciate any help you all can give. Thank you!!!