I have created a report that shows created, open, and closed tickets per month. The problem is that it shows open tickets only for that month, and not total open tickets by the end of the month.

 

Example:

January

39 tickets opened

35 closed

9 still open

 

Basic math tells me 9 are still open. This report doesnt tell me about the other 20 tickets still open at the end of January. It should say around 29 tickets are STILL open. So it needs to show previous open tickets from earlier months.