The graphs here depict when newly generated coins first moved (up to block 250000). The Y axis is the mtgox weighted value for that day, with the X axis being the block number from where the coinbase originated. For example, X starts at block 9 which contains Satoshi's address 12cbQLTFMXRnSzktFkuoG3eHoMeFtpTu3S. These coins were first redeemed in block 170. We are not interested in block 170, but rather that it contains a transaction with an input from a coinbase.
Horizontal lines in the graph usually indicate redemption of coinbases within a single transaction (or nearby transaction/s). Redemption does not necessarily equal coin ownership, however coinbase spends are something I find interesting to plot.
Density is difficult to display due to the size of the data set. The red selection (blocks 180000 - 220000, < $40) is shown in the second graph.
It would appear that coinbases were redeemed more quickly from 2011 onwards. Perhaps this is due to pools having to pay their miners.
Click for full size images -
http://www.filedump.net/dumped/graph2xx1380330890.pnghttp://www.filedump.net/dumped/graph31380330890.pnghttp://i41.tinypic.com/15ob71v.png
