Hayden,

On the far right hand side of the column in TCR, right before the date of issue, you will often see a number in italics, that is a population indicator. Often the exact number of chips is unavailable (assume there were many in most cases). The more modern chips and particularly the limited editions are much easier to provide a population. Occasionally there will be a negative number and this, as i understand it, is if a significant number of chips were confirmed to be destroyed. Remember, it is nearly impossible to determine the existing population of any chip and even then, the number will change as chips surface from unexpected sources.

As for the prices, I am not privy to the algorithm that SSS publishing uses, but I imagine it is based upon sales observed on eBay, at auctions, and via website sellers and convention results. Prices change constantly and can be quite dramatic when comparing prices that are based on data points of a decade or more. Sometime, all it takes is a single collector to pay premium prices for a few scarce chips to drive a price up significantly, or a single box of chips to be made public to drive prices way down.