The Flynn effect is an observation that IQ test scores tend to rise among the general population (and among many subpopulations) at a rate of about 3 points per decade. The cause of this trend has been the subject of much debate. Despite this, I found it difficult to find standard deviations or other moment statistics over the time period studied by Flynn. Aside from the increased knowledge of IQ testing today (which would cause more of the gifted to get tested and presumably raise the mean score), there isn’t any reason why more would test gifted. However, it’s possible that improvements in medicine have prevented many from falling below the mean due to disease (congenital or early developmental, most likely). These stats would allow testing of these hypotheses.