[esteem_lover]

The reasons could be

1. Old & hard rubber on the blades
2. Bent & out of shape wiper arm.
3. Windshield has too many big scratches.

or all of the above.
go about eliminating one after the other. First replace your blades. the esteem blades cost about 300-350 for a pair. If it is still there, replace the wiper arms. This should be enough. else check for deep scratches in your windshield.
cheers