Working out average frequency of a purchase

[Lifestyle889]

Good Day, 

I am looking for some assistance in working out the average frequency of a purchase of our customers. E.g On average a customer makes a purchase every 19 days. 

I only have the below data for the year:

Customers	Transactions	Transaction/Customer
142036	1657801	11.67169591

This is a high level understanding and not something that should be able to be applied to each individual customer as I know that would require individual transaction rows with time and date stamps. 

[#2]

@Lifestyle889 

You might use

=365/(transactions/customer)

[#3]

Thank you!