Auto insert of rows

What I need is a simple macro that looks down one column in a page and if the content of the cell is different from the one above it inserts a row. So say column B reads 1,1,1,1,1,2,2,2,3,3,3 it would insert a row between the 1s and the 2s and the 2s and the 3s. This is so I can group together sdimilar data. I have given a brief sample sheet of what I would like. Could someone please give a rough idea of how I can do this?
Many thanks,

Jack