Forgive my piss poor data management skills... but if the chances of something happening are 4%, then the chances of it happening twice are 4%x4% (0.04x0.04=0.0016) or 0.16% and the chances of it happening three times are 0.0016 x 0.04 = 0.000064 or 0.0064%. Is that right?

So 1% is 1 in 100
0.1% is 1 in 1,000
0.01% is 1 in 10,000
0.001% is 1 in 100,000
so 0.0064% is 64 in 100,000 or 1 in 1562 turns? Is that right?

I've played 3519 turns so far this set. Obviously I haven't had 4% tech from the start.. but according to my admittedly poor math a techer or someone who maintains 4% warfare from the very beginning should expect to see 3 missiles on average 2 or 3 times a set?