Lisa, I would say that 75% of my prayers are answered affirmatively; more are answered than not, which indicates to me that it's more than just chance.
As for the prayers that are not answered, I believe it's because I've asked for something Jehovah doesn't want at this time.
Small prayers are answered rather routinely. Big prayers take more time and effort, and I'm less likely to get a favorable response.
Small prayers, like getting a list of congregation members; and big prayers (for me), like not having to take the DMV written test when my DL was renewed, which I was really worried about.
Although it's a lovely thought, the universe is incapable of granting prayers. No.