I installed a plugin “import and export users” and exported users for current year in csv file.
Then I opened the file in excel and removed the unwanted columns keeping only name and email column.
I then created a new list named users2020 and imported the csv file with following settings
Import subs as: confirmed
import mode: update
Uploading the file did not work so I opened the csv file in text editor (not excel) and copy pasted the email,name vaues to the csv text box.
Clicked import and it was done !