Calculating Incremental GMs

Hello, this is a simple question but any help understanding GMs vs incremental GMs is appreciated.

I did a screening for the following:

Mid-Cap Stock, Revenue Growth positive from 2022-2023, Company must have reported their Year End Results, Positive Gross Margins. (Does NOT need to be rising, just positive).

Then I have to calculate the incremental GMs for five of those companies.

Do I use 2021-22 data for this, or 2022-23 data? If 2023, how would I go about doing this?

Thank you, I appreciate any help!