Formula to pick up last 6 months data.

Hi.

Is it possible to build a formula in excel to sum the last 6 months numbers on a different worksheet and next month it rolls forward so it again captures the last 6 months?

In my attachment, (Summary tab, cell H7) I want to sum the figures in the raw tab for past 6 months. I.e I9+H9+G9+F9+E9+D9

Can this be automated via way of a formula or can only be done via VBA?? I know how to sum the cells, but just want to know if this can be automated so the formula automatically rolls forward.