Your perception of how many bottles are corked probably depends on your
sensitivity to TCA. A decade ago a friend of mine, a former chef and critic,
told me that he thought the standard estimate of 5-10% was way too high.
But further investigation showed that he was relatively insensitive to that
particular scent, either that or was used to it. In my experience, probably
close on 10% are corked, but many of those are potable anyway.