Democrats good for economy?

According to an article on Slate the S&P 500 has grown more under Democratic presidents than Republican ones. Democratic presidents produced a 12.3% return on S&P 500, versus an 8% return for Republicans. Bah you say, the stock market doesn’t indicate economic growth. Well, GDP grew 5.4% under Democrats and 1.6% for Republicans. Listening: 19-2000 Gorillaz