Measures for Employee Retention

Hi Everyone, i am very new to Pbi so i may be asking a stupid question but need help creating the appropraite measures to calculate and display employee retention. i know the calcuation i want to do (see below) but i am stuck on how to replicate this in a visual. Ideally i would like to show the rate by year, including the current year. 

(Employees at end of period - new hires for the period = retained employees) Retained employees / employees at start of period x 100

Thanks!