yes its normal, if you don’t accept the data quickly enough other storagenode’s does and reports that it has received the transfer and when enough have done that the rest are cancelled.
the amount of these will change depending on how loaded the storj network is…
if there is lots of work… more nodes get more work and is busy, so the slower nodes will see a pickup in their successrates.
its very normal… regular ratios are somewhere between i duno 20% minimum to 80% max for most nodes depending on a large number of factors.
Sometimes the file is already fully transfered when the cancel comes in. In that case it will remain on your node and you will get paid for it as well. You can also get downloads for it as normal. So basically you finished just in time in those cases to still be counted.