How full are the blocks and what metrics can be used to measure it?

I suppose that this question gets very different answers on /r/btc and /r/bitcoin, but let's give it a try :-)From the "fee market"-perspective, the question can be rephrased to "how much does one need to pay for getting the transaction through". If this number is growing rapidly, we have a problem. If this number stays reasonably low, then things are cool.I think the best would be to look into historic transaction data and make some statistics on fee/byte vs how much delayed the transaction gets mined. The transactions doesn't contain any timestamp, but i.e. blockchain.info seems to store the received-timestamp for every transaction. I would like to play a bit with this, but I'd like to ask for comments first. (there are so many different metrics, important to decide "what should I do with this data" before collecting data, it's always possible to find data that supports a hypothesis if first deciding which hypothesis is right, and then searching for the right data).The indirect approach would be to use historic estimation data from cointape. I've thrown up a crontab that fetches the data from cointape every hour, since 2015-11-06. The fees and mempool was growing until mid-December, then there was more than a month of downtime, and when cointape came up again the fee estimates was pretty much lower. I suppose there may have been a bugfix or algorithm change, i.e. throwing away non-mined transactions after 48 hours?After 2016-01-15, the recommended "fastest fee" has been mostly jumping between 30 and 60 satoshi / byte, 50 being the median and by far most normal value, some few times I've observed higher values than that, but never sustained for more than an hour. The average "fastest fee" seems to be climbing. (I'd like to publish a graph, but may need some help on getting the dates correctly on my pyplot graph, I didn't quite get it right). via /r/Bitcoin http://bit.ly/1XRxjSp