Actually by statistics, to have a confidence level of 95+-10% for 7million people, you need a sample size of 96. It goes up sharply if you need 95+-5%, for that you'd need a sample size of 384. All this does not include high bias trends. If the trending statistics are in the 10% level, you only need 139 to reach a 95+-5% confidence level. At 5% 73.