Interesting graph. Looks like people started saving their bitcoins in 2011/3.
That march spike is actually an even smaller spike in week 9 (beginning of march), as you can see in a weekly breakdown I did:
https://bitcointalk.org/index.php?topic=37422, where I speculate that this is the MysteryMiner keeping his coins.
Any chance you could add the number of bitcoins in existence + market value in the same graph?
I've thought about adding the amount of coins mined in each month. (Consider making a small donation if you want to increase my motivation: 1SQL2R5ijCn2ZiBG8aDYpCiecNPuxzMJJ)
I could also add the market value, if I had the data. Can anyone help me with that?