I am trying to average a list of numbers in the second table based on which quarter and year they fall into. 1st quarter of 2003 corresponds in the table below to 1/01/2003, 2nd quarter of 2004 is 4/04/2014, etc. In my second column I am trying to get an average of the second column of the second table below based on if the month is 1 2 or 3 for 1st quarter, 4 5 or 6 for second quarter, etc. and if the year matches the year in the Quarter column. Any Ideas?

[TABLE="width: 500"]

<TBODY>[TR]

[TD]Quarter[/TD]

[TD]Average Return for the Quarter[/TD]

[/TR]

[TR]

[TD]1/01/2003[/TD]

[TD][/TD]

[/TR]

[TR]

[TD]4/01/2004[/TD]

[TD][/TD]

[/TR]

</TBODY>[/TABLE]

[TABLE="width: 500"]

<TBODY>[TR]

[TD]Date[/TD]

[TD]Return[/TD]

[/TR]

[TR]

[TD]1/4/2003[/TD]

[TD]127[/TD]

[/TR]

[TR]

[TD]2/5/2003[/TD]

[TD]120[/TD]

[/TR]

[TR]

[TD]4/3/2004[/TD]

[TD]159[/TD]

[/TR]

[TR]

[TD]5/23/2004[/TD]

[TD]161[/TD]

[/TR]

</TBODY>[/TABLE]