What is the practicable way to free exams. from the vice called Malpractice?

I have worked 10 years as a teacher in a college.I have found 98% of my students below normal standard.After query It was found that all of them have come so far only by copying answers in their exams.They hardly study.Their parents and teachers too have encouraged it.This is the educational environment,they have been brought up in since cl-1.To add to the woes most of the schools and colleges in that area are affected by this malady.I left the job and now I am engaged else where but the memory haunts me.Little Children are addicted to copy as if it is opium.They can't do without it.