It was not uncommon to get data that varies by factors of 1000 over the course of the chart. In order to see anything useful on the chart, it was necessary to use a logarithmic scale on the block generation charts, the minted currency chart, and the transactions chart. Taller bars are exponentially larger than shorter bars. So pay attention to the units on the left and you can hover over bars to get the precise value. Rarely, there are data values between 0 and 1. Due to the mathematics of logs, these show up below the x axis.
Time Periods are calculated from the starting block's time. For example, if the starting block time is 08:45:00, then hour 1 is from 08:45:00 to 09:44:59 and hour 2 is from 09:45:00 to 10:44:59. Right now, you can't see the start and end time of a time period on the chart but you can see it in the "Raw Period Data" which is linked to at the top of the page.
Sometimes there is a large gap in time between the genesis block and the first block. This would lead the "first 96 hours" chart to be empty. In those cases, I've changed the starting block so that the chart shows the more interesting part where blocks start to be found. Sometimes, the genesis block is reused from a previous currency. In some cases, this causes an empty gap of over a year. In these cases, I've started all charts for that currency from the first block instead of the genesis block. Check the "First block processed" field at the top of the page to see if this is the case for a particular page.
The difficulty indicated for a time-period is the average difficulty over that time period. This means that the indicated difficulty may not correspond to an actual difficulty that occured.
Network hashrate is estimated based on the number of blocks found in the time period. This estimate does not include orphaned chains. If difficulty was low and there were many orphans, then the actual hashrate would have be higher than indicated. If no blocks were found, this will show 0 even though there may have been hashing.
Sometimes fees are double counted as new mint. This results in a small overestimate of the total supply. This affects smallchange, nibble, luckycoin, americancoin, phenixcoin, digitalcoin, stablecoin, since the block reward is being calculated from the coinbase transaction for those currencies and it's difficult to remove the fees.
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