Seperate a huge data set into weeks, and average them

[zcfad93]

Im short for time, and have a massive data set that i need to seperate. The data is in this format:

Cell A Cell B
01/01/1977 4.5
02/01/1977 7.6
03/01/1977 7.7
04/01/1977 9.0
05/01/1977 3.4
06/01/1977 12
07/01/1977 7.2
08/01/1977 4.6
09/01/1977 7.9
10/01/1977 4.5
11/01/1977 5.5
12/01/1977 6.6

It is a daily data set, which goes on for 30 years, so approx about 15 000 cells long. I need to seperate it into weeks, and then average out the weeks. Is there a formula to do this?

Thanks

Omar