This chart is missing something? Like strength of the economy (and what measure are you using to measure the economy in each of those years?)
IMHO, you can not strictly base the functioning of the economy off of tax rates. it is so much more involved than that.
One could argue, that based off other factors, the economy would be much worse off than it currently is if tax rates had been higher and lowering the tax rates has kept if from getting worse.
Too many variables in play to but the onus on one thing.
Just my 2 cents.