I have a column with id, it has repeated items and columns with values. Data are like week 1, week 1, week 2, week 2, etc. I need to create a table where for week 3 I have an average value between 2 whole previous weeks (week 1, week 1 week 2, week 2), for week 4 I have an average value between week 2, week 2, week 3, week 3 from the original table etc. How can I do it in Power Query.