How to Compare row values using another row value - see description

Hi All,

I have data like given below. I am trying to compare the latest year (ie 2018) data with 2017 and wanted to know if there are any new models added / deleted in the data. In this data we can see 102 got deleted and 105 got added. So I am trying to create a calculation where it shows one data got deleted and one got added, This calculation should work for rest of the months as well like feb 2018 compared to feb 2017. How can I do this? 

Product Desc            Product Model

Jan2017                    101

Jan2017                    102

Jan2017                    103 

Jan2018                    101

Jan 2018                   105

(1) Answer