Who is better with the economy?

I keep hearing conflicting things about who is better for the economy, a democrat or republican. Under Bill Clinton, the economy did great, but the other side argues that the tech boom was responsible for this. I find it to be highly coincidental that under Reagan the economy struggled and amazingly the economy improved under Clinton and suddenly became bad again when GW took over. I would like someone to present proof, i.e. doents, websites with doents, etc., which proves that the democrats were just lucky during the Bill Clinton era. Its just that I find it to be greatly unlikely that there is some sort of economy "switch" which turns from bad to good when a republican/democrat is in office.