Agreed for 2013, I was just puzzled by the last 3-4 months of flatness (by bitcoin standards!). In a way you're reinforcing my question; the 2013 rise was through a huge increase in demand. It seems nothing got in the way of the overall price rise.

Great explanations / hypothesis everyone. My takeaway is that although aggregate demand is steady(ish) transaction volumes may indicate a rotation of ownership as franky1 indicates.
Just had a look at the transaction charts here
https://blockchain.info/charts/n-transactions-excluding-popular?timespan=60days&showDataPoints=false&daysAverageString=7&show_header=true&scale=0&address=
but I can't conclude with confidence it supports the rotation hypothesis....will stare at it a bit longer