Let’s break apart the words here. Atheist basically means without gods or without theism. In contrast agnostic means without knowledge. Let’s stop putting these on the same spectrum because they deal with different concepts. I like to clarify by distinguishing between nontheists and atheists. Those who have not made a decision on their position with respect to theism (whether they are a theist or atheist) are nontheists. Those that have taken a position are either theists or atheists. Now with respect to agnosticism regarding theism either you go around telling people you KNOW for certain there is (or is not) a god., in which case you are a gnostic, or you take the position that you can only reach greater and greater degrees of certainty based on the availabile data, in which case you’d be an agnostic. I’m an agnostic atheist. I’m BOTH.

my .1% stance is based on Sagan's reply to a similar question; that it is arrogant to claim with absolute certainty either proposition. And while I see no evidence for a god, I am not a perfect instrument to measure this. That, or there IS a god, and they suck at what they're supposed to do.

The burden of proof is on the proponent! And I didn’t think you can be 100% sure of anything. If you say you are 100% sure then the burden shifts to you to prove a negative! I do feel comfortable proving a negative with the common understanding of the Christian god. That’s because Christians often assert mutually exclusive claims dogmatically.

Nothing is 100 percent except for death.

99.9% is scientific nomenclature. I'm as sure there is no God; as I'm sure that if I drop an apple, it won't "fall" up.
Pascals wager has always struck me as meaningless. Here's why.

Will you go to hell for not believing in God? Most Abramic Religions say yes. If the answer is 'No' than there are no repercussions. No need to pretend to believe.

Does God know everything? Almost all religions say yes. So if God is Omniscient, he knows you don't really believe. You're still going to hell. No need to pretend to believe.

No, at least not for me. My reasoning for being 99.9% sure that no god(s) exists is due to the fact that although we know all the gods that are believed in around the world are all manmade and therefore mere fabrications, I cannot be certain that no god exists outside of human conception/fabrication. Of course, this is the same as me saying that I cannot be certain that no fairy tale creatures exist outside of human conception.

tell if you go by the scientific theory you can never be 100% closed off to new data. For instance you ask is some one believes in Unicorns, they say 100% no. Then we discover a unicorn fossil. Dose that person still not believe in unicorns? no, we now have evidence to support unicorns. If they continue to say their were never unicorns its the same argument theists do when confronted with evidence their religion is wrong. But ya Science don't care what you believe to be true, its only concerned with evidence of what is true, so you must always be open to new evidence.