I have at least one question that I'm the only person to provide an answer to.
I haven't accepted my own answer. (I couldn't see the point, to be honest, obviously I think it answers the question, and - in the absence of any other answers - it's the best of the answers that answer the question, there's no need to signal that.)
However, it occurs to me that maybe that is a problem from the point of view of making the "questions with no accepted answers" rate worse (and my own acceptance rate, come to think of it).
So I suppose I have a three-part question, though answers to any portion will be of interest:
As a general principle, should you accept your own answers in order not to make the accepted answer rate lower?
Is there any other reason to accept your own answer?
Is there any reason you should avoid accepting your own answer?
Edit: I note that there's an additional delay on accepting your own answer to give other answers a chance to be accepted. In this case any such interval is long past.