Hmm, I've checked that file, I see what you mean - headers are messed up, while the data itself is fine. I'll fix that soon.
Historical data - hmm, we're saving data daily, but it's not available online, only by request. I can get it for you if you need, just ask. It will be daily per-minute CSVs, but it's not going to long in the past, as we've started tracking global averages not so long ago.
Alex at BitcoinAverage