In animal testing labs how many animals die a year but for a good cause?

All of the animals that die in labs die for a good, life-saving cause. No one knows how many die because of the secracy that has to surround them for the safety of the workers there. However the number is just over half of what it was in the 1970's due to new computer technology.

I say not because it makes the animals population drop!!that's not a good thing!!