E - understandable. Most used letter in English.
A - understandable again. A vowel and a home key.
S - again - a commonly used letter and a home key.
N - Huh?!?
On the right hand side of the keyboard the only keys to suffer this fate are the full stop and the letter N. Why the letter N? I don't type that many words with Ns in them. It's not a home key. I don't have to pass it on the way to the space bar or anything. I really don't understand this.
Beyond the scrape marks (and I just noticed that the letter I has been affected slightly) there's the issue of the letters wearing off the tops. This doesn't matter as I touch type but I've lost the N, most of the M and the O. D is half there and H is fading. Despite the slashes A is mostly there, as is E. The numbers are fine and the F keys across the top of the board are used so rarely they have a layer of dust across them.
And this concludes Keyboard 101. Discuss.