Token for Years since X occured

I was tasked with creating an anniversary-style email for our members.

What I am wanting to do is take the existing lead record field Mbrship Open Date, which is when the member joined and create a token for how many years have passed since then. For example, say your Mbrship Open Date field said 3/9/2020 the value of the Token would be 2. That I could use in the design of the email.

It feels like this may have to be a velocity script, but perhaps maybe it can be done using a smart campaign and a new field that is "years since membership opened" and have the flow step populate that value... I just don't know how to do it, if it was possible.

Thanks