Counting Dates that fall within a certain month

Please open the xls. file I've attached to help understand me problem.

I have items arriving on certain dates (the dates are listed in column N)

In the cell to the right of each month, I want to have a formula that will count the dated cells in column N that fall under each month.

i.e. In cell B5, next to January, I want to display the total number of cells that contain a date in January (ultimately giving me the number of items that arrive in January) the number would read '5' because there are 5 dates in January that are in the list.

How can I accomplish this?