use strict;
use warnings;

# initialize averaging
use List::Util 'sum';
my $size = 10;
my @store;
my $i = -1;

while (1){
  my $line_count = int rand 100;

  # store data and output average
  $store[ ($i+=1) %= $size ] = $line_count;
  my $average = sum( grep defined, @store )/$size;
  print "Average line count: $average\n";
}