However ...
The output from a single "iostat" without parameters is totally meaningless.
It may be better to invoke "iostat" once with parameters to cause it to sample for the period you require at the intervals you require. Beware that like "vmstat" the first set of statistics (whatever the time interval) should be disregarded.
IMHO it is worth the effort and disc space to set up "sar" (see "man sa2") if you want basic system performance statistics.