Excel: averages - Ignoring some cells

I need to chart the average of some data over a number of months. For example, I have 12 columns, Jan to Dec. In each month is a percentage. Jan - 46% Feb - 25% Mar - 60% Apr - 55% May - 47% June - 38% Now, I need to calculate the average of these percentages, which is easy aprt from this. I need to take the average of all 12 months, but only include the months will good data, ie, jan to jun. July to december has a formula in there but not good data as yet. So when data is good for July and entered this will become part of the average. As it is now my average takes into account all 12 months therefore incorrect. All help appreciated.

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This thread is current as of June 26, 2015.

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