You could also sample the number of transactions per second and adjust this parameter to accommodate the peak number of transactions per second (or some large percentage of it).
And although there were more children with higher cognitive ability in the 2009 sample, the percentage of such children was only slightly different (59% compared to 54%).
Yes I might have only made one or two , but structurally when I said here how many people did we sample in this population and what percentage of the population is that?