I'll just point out to you, yet again, that the gap between the US and Singapore is almost completely explained by ethnicity. Asian Americans have test scores only marginally worse than Asian Singaporians.

http://super-economy.blogspot.com/2011/01/how-well-do-above-...

In terms of test score ranking, the best test scores come from Asian Americans in CT, closely followed by Asians in NY and TX. (As one might expect, CA underperforms the US and Singapore.)

Similarly, Americans of European descent rank #6 among Europeans of European descent.

http://super-economy.blogspot.com/2010/12/amazing-truth-abou...

I don't know why you refuse to acknowledge this.