Is this what you want, as tye pointed out,

#!/usr/bin/perl -w
use strict;
use Smart::Comments '###';
my $report ={};

my @strings = qw(
0101
0001
);



for (@strings){
        my $string = $_;
        $report->{$_}++ for $string=~/../g;

}

### $report

### should be
### 01 3
### 00 1
[download]

Or should the result be 01=3x, 10=1x, 00=2x ?