UE was 10.0% at the bottom of the Bush Depression and is 5.1% now, a drop of 4.9% and falling.
What has that got to do with growth?
Three Decades of Empirical Economic Data Shows That Supply-Side Economics Doesn’t Work
The Failure of Supply-Side Economics
Supply-Side Economics has barely been tried for anyone to either prove or disprove.
Supply-Side Economics is often confused or compared with Trickle-Down Economics which has also never been tried and does not exist.
Supply-Side economics has been tried in very few parts of the Earth.
If you really want a good example, take a look at Hong Kong. It's practically the lowest taxed country in the world and had pretty much taken a stance of non-interventionism/non-protectionism on almost every sector of their economy and it is considered one of the most prosperous countries in the world with a very high standard of living.
Supply side economics is made up by the Democrats to discredit economic freedom.