"There are 1,786,752 different addresses in the block chain. That's less than 0.000000000000000000000000000000000000001 % of all the addresses that can be generated."

But I used 2^160 ~= 1.46e48 as the total number of addresses (Because addresses are stored as hash160s internally, and I assume every hash160 is a valid address ; if I'm wrong then correct me!).