How many converted to atheism in a year?

People do not "convert" to atheism, because there is no central authority of atheist opinion to swear allegiance to as there is with some religions, nor the typical habitual practices that most religions demand. There are moral atheists and amoral atheists. If you were asking for example "How many people lose their trust or faith in the Roman-Catholic church in a year?" you might be closer to an answerable question.