#!/usr/bin/perl
use strict;
use warnings;

my $total = 0;
my $num   = 0;

while (my $line = <DATA>)
{
   my @tokens = split ' ', $line; # split removes line ending
   next unless @tokens == 3;      # ignore blanks and header line
   
   $total += $tokens[-1];  # add last column
   $num++;
}

print "total = $total  Average=",$total/$num,"\n";
# prints: total = 127297  Average=31824.25

__DATA__
CHECKPOINT

2017-08-01 20MICRONS 37744

2016-08-01 20MICRONS 25966

2016-04-20 20MICRONS 30807

2016-04-01 20MICRONS 32780