How many animals are used for dissection per year?
There are no certain statistics about it, only rough estimations.
According to the Nation Anti Vivisection Society in the United States, the number of animals used for classroom dissection (up to collage level) can rough up to 6-10 million per year. And that is in the US alone.
Please clarify if you require statistics from other countries or the inclusion of dissection for non-educational purposes (research institutes or pharmaceutical companies).