VPLEX Monitor counter units - KB/sec

I am trying to monitor writes to a virtual volume in order to calculate WAN bandwidth utilization after mirroring.  I'm confused on the units being reported, though.

I'm setting up the virtual-volume.writes monitor every 5 seconds and a file-sink.  Then I'm using the CSV output and charting with Excel.  The data collect and charting works great.  However the units reported are supposedly Kilobytes per second. 

What does this mean exactly for a 5 second (or 30 second, or 5 minute) collect?  Is this total number of Kilobytes written throughout the collect period?  Is this an average KB/sec write rate throughout the period?  Is this the maximum KB/sec write rate during the time period?  It is odd to me because you don't generally have a per second write rate in a cumulative counter. 

Thanks for any clarification on these units.