You can use code from answers to your previous question and add a little check for the variable containing the value of -s parameter, something like this:
defined $statfile && open my $FILE, ">", 'last_5min.stat' or die $!;
<...>
defined $statfile && print $FILE "<ED>$by</ED>\n<ECO>Max Busy</ECO>\n<
+ECE></ECE>";