Statistical interpolations are worthless.
This is very true. We have no way of knowing whether or not Rally Sports, for example, were equally distributed through out the entire number of Camaros built. But, statistical interpolations are kind of fun to do anyway, so so for our new curious owner above:
Let's say we have a big jar full of all the Camaros made in 1969 (243,085). We know that there are 20,302 Z/28's in there. If you could reach into the jar and pull out a Camaro, the odds that you would pull out a Z/28 are about 1 in 12 (20,302/243,085). To pull out a Rally Sport the odds are about 1 in 6 (37,773/243,085). These are valid statistics because the numbers are known. Now, just for fun, let's assume that the Rally Sport option IS equally distributed throughout all of the Camaros in the jar, i.e., a normal distribution. This is assuming that it's just as likely that any Camaro made would have the RS option. For example, this assumes that plain jane 6 cylinder Camaros were just as likely to get the RS option as a Z/28, or an SS, or a convertible, or any other 1969 Camaro. We know that's probably not true, but let's assume it is for now. So then, the probability of pulling out a Rally Sport Z/28 out of the jar is .013 (20,302/243,085 * 37,773/243,085) or about 1 in 77. So, using only one assumption (and it's a big one), we could guess that there would have been only about 3,160 Rally Sport Z/28s made in 1969 (0.13*243,085). If the assumption is not too far off from reality, a real RS Z/28 is fairly rare.