Auto lookup and sum month totals

[freud1]

Hi Guys,

I have a table which holds a grid of data (see attached spreasheet)

On the next sheet I have a table which I polulate with the sum of the month for each column.

I need a way to auto populate these based on the data present.

There will never be more than 365 days worth of data however this data could fall between any dates.

I need the second sheet to firstly populate itself witht the months which fall within the date range, then to sum the relevant column for each given month.

Any help would be much apreciated.