I hate it.......

I share a office room with one colleague. There are many tables in here and i use one table only. My colleague takes a seat after my back and he has 3 tables around him. However I always have to move his things such as a bag, coffee, documents, etc... out of my table whenever i go to the office. I hate it... i do clean my table whenever i go home and i expect to see my tidy table in the next morning... I told him about it but he still does it..with a bad excuse is he forgot about it.