Building a Report based on how many contacts had a similar checkbox selected based on a given date

Building a Report based on how many contacts had a similar checkbox selected based on a given date

Hello,

In my CRM under contacts module i have a checkbox called "Active" I want to be able to see how many "Active" Contacts I have based on a given date, For example in the month of August how many contacts were marked as active, then September, then October then i can start to see yearly trends of how many contacts I have active at any given time. 

I'm trying to do this in Reports but can't find a way, do you have any suggestions or possibly a workaround so I can begin to build this trending.