DJ
I have lived in East Tennessee for almost 20 years, and have encountered (approximately) the following large native snakes:
# Snake
4 Black Kingsnake
1 Milksnake
4 Corn Snake.
6 Black Rat Snake
12 Watersnakes
6 Queensnake
5 Black Racer
2 Copperhead
9 Eastern Pinesnake
0 Timber Rattlesnake
38 Total
5% Copperheads
This is off-the-top-of-my-head, and skewed by my personal experience, preferences, and ability at finding snakes (or lack thereof), but it should give you a feel for how common these snakes are. It suggests to me that Copperheads are not uncommon or rare, although perhaps not as common as some colubrids.
Hope this helps 
John D
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I am so not lesdysxic!
0.1 Creamsicle Cornsake "Yolanda"
1.0 Bairds Ratsnake "Steely Dan"
0.1 Desert Kingsnake "FATTY"
0.1 Black Rat (WV Rescue) "Roberta"