It is common in Excel to have columns of months, quarters, weeks, or years. But those data sets make horrible pivot tables. You really need one column with the time value and one column with the sales value.
This episode shows how to use Mike Alexander's Multiple Consolidation trick to unwind the data, but there is a twist; this data set has 3 columns of labels. Update! If you have Excel 2010 or Excel 2013, there is a faster way to solve this problem using Power Query. See