This output layout change was necessary because systems with high traffic had the output become practically unreadable due to a KiB per hour value no longer fitting within the available space. As a result, dynamic unit selection was introduced in vnStat version 1.13. Starting from version 1.18, the hourly output can be a little bit configured using the HourlySectionStyle and HourlyDecimals configuration settings.
Note that you should never try to parse the textual outputs in scripts as the layout isn't guaranteed to stay exactly the same from version to version and will also vary somewhat depending on the used system locale. Instead, use the --json, --xml and --oneline outputs which have a machine readable structure with versioning. The output version of these three is also important to check as the structure is slightly different in vnStat versions 2.x due to more data being made available. PS. reporting this directly to upstream would have resulted in a faster answer. -Teemu
