I have two fields RegFrom__c and RegUntil__c.

I would like to calculate how many calendar years there are between 2 dates WHERE:

CertRegFrom__c= 01-06-2018
CertRegUntil__c = 02-06-2023

This is a period of 5 years, but 6 calendar years, so result of the formula should be 6, the formula below returns 5. 

between the dates above you have the following calendar years 2018, 2019, 2020, 2021, 2022, 2023.

If CertRegFrom = 01-01-2018 AND CertRegUntil = 31-01-2022 then the formula must equal = 5
 

(CertRegUntil__c - CertRegFrom__c) /365

Can anyone help me adapt this formula?

Dave