YTS Week by week comparison

[Daniel1984]

Hi,

I am trying to create a table that shows how the percentage split between refundable and non-refundable bookings has changed over the last quarter. What I am struggling with is creating a dimension that shows YTD data per week over the last 12 weeks. I have created YTD data before but creating a dimension that does this for each of the previous 12 weeks is proving a challenge, any help here would be much appreciated.

Thanks,

Dan