My first thought at looking at all this is to wonder why people are assuing that all four races have the same number of years per generation, and why all four races have equally strong reproductive urges. In some cultures, one offspring is enough. Other cultures may be more into large families. I think it safe to say that each race has it's own, unique culture and therefore differing standards on how many offspring to have. That will have an effect on population growth.
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Do not assume that you speak for all just because you are the loudest voice; there are many who disagree that simply have no desire to waste words on you.