Have you ever seen the rain, strum pattern

Hi hope some one can help with a suggested strum pattern for  have you ever seen the rain' by Creedence Clearwater Revival. I've been learning for a short while but have got in a rut with one strum pattern and can't seem to move away from it !

any suggestions would be helpful.  Also I've got to say this is The best site both for tab and for people helping.