Are BTC Private Keys evenly distributed in 256bit space? If we assume that there are ~2^96 private keys for EACH bitcoin address (2^256-160) and we assume that in cryptography it is considered good property of every hash function if it evenly distributes the values in its co-domain (co-domain of the SHA256 function is the domain of the RIPEMD160).

Does that means that HALF of the ~2^96 private keys is in first 2^159 and other HALF is in 2^160 - 2^256 space?
The random number generators that generate private keys should follow a uniform distribution as this is the distribution that maximizes entropy. 

As the private keys that are used are not known we can't measure if the keys in use have been statistically speaking distributed uniformly.