Price elasticity over years, semesters, quarters, etc - Midpoint method

Question

I'm trying to calculate price elasticity using the midpoint formula over different years, semesters, quarters, etc.

Taking in consideration the formula:

Midpoint method

Let's say we have this data:

Applying the formula on data

            2020        2021
Quantity   7129470    6839959
Price       10.37      10.49

So, quantity is the sum over each year (sum for 2020, sum for 2021, etc) and price is the average price for that year. If we want to calculate the elasticity between 2021 and 2020, should we use sum of quantity and sum of price for both years? Should we use their average instead? Or can we still use the sum for quantity and average for price?

Thank you