I am comparing this month's (February 2013)  daily sales to last year's (February 2012) daily sales. I currently have the February 2012 and 2013 sales by day as well as a % of total column (using "quick table calculations"), showing what percent of each month's total sales came in each day (both incrementally and cumulatively).

I want to do a sort of forecast to see how our current run rate is compared to last year's, and where we can expect to end the month based on that current run rate. Is there a way to take the number in the "% of total" as calculated in the "quick table calculation" and apply it in my own calculation? Or somehow calculate "% of total" in a calculated field?

I'm attaching an Excel sheet that approximately does what I'm trying to do - it can be a bit confusing to explain in writing.