Oh dear...

Tut tut, fall asleep in school when they covered compound interest did we? ;)

Double your 2021 figures, and that's round about what you get for a 50% increase per year (which, incidentally, I think is an underestimate). So, 4TB memory sticks and 64TB SSDs and HDs all around by 2021. Or not much later than 2015 if you ask me.

It's also interesting that you felt the need to plug the exact same figure into the exact same formula twice (SSD & HD) to work out that we get parity. :)