Rear wiper

Hi ya

I have a problem with my rear wiper. Only the very bottom of the rubber actually touches the windscreen.
Does anyone know how this could have happened? I only bought the car recently. Could it be that a wrong wiper arm is fitted and I need to get a new one? Or could it be bent? Or does it just need a new rubber?
The top section of the wiper when it points upwards in the middle of the screen is lifted about 5-10mm off the glass.

Thanks.