Calculate backdated cumulative 'open' records

Hi all, 

Seen a few similar posts about this but nothing that I've been apply directly or get my head around. 

My table ('Logged') contains entries for indivudual records including colums for 'URN', 'Date Received' and 'Date Closed'

I need a measure that works out the number of open records at the end of each month so for every month this would calc:

Count rows if 'Date Received' before the filtered date AND either still open (i.e. ISBLANK('Date Closed')) or closed and 'Date Closed' is after filtered date.

Hope that makes sense!