If you see the signature of any user at Stack Overflow, it tells you the acceptance rate beneath the name. Look at mine and you will see 79% accept rate. I tried to find which questions I have asked but not accepted. I found that there are some questions which were answered and yes they were correct in respect of the question but not what I was expecting. For example:
In such cases should I accept the answer with highest votes or should I leave them as it is? After all these questions are affecting the acceptance rate. Also does this acceptance rate matter to you?