Consider the sentence
E-books are on the rise, but they haven't suppressed paper books though.
This usage seems to be quite common, but when I learned English I was taught to use "however" where I now read "though".
My questions on this use of "though" are:
Is this a new trend?
Is it restricted to American English?
Is "though" considered more colloquial than "however" ?
And on a syntactic level:
Do you put a comma before "though"?