Statistical significance does not mean a law in the sense of physical sciences. It does not mean we don't have outlier cases like Singapore and India. We do have to regard these outlier cases seriously, but overall statistics tell you that these two variables are positively correlated.
Mind ya, Norway, the richest country in the world, is a socialist country. And now we see the former East European countries who began to embody socialism and economic boom at the same time. They are joining the EU now, with the socialists going back to the government.