Use 6 portals placed side by side, one for each month. Portal filtering can be used to limit the records shown to those from a specific month. (And the specific month, year can be controlled from a single drop down list or pop up menu so you can select different 6 month intervals on the same layout.)
This does require exactly the same types of records (price, consumption, etc.) in exactly the same order in each portal in order for the rows in the different portal controlled columns of data to match with each other.