my $fmt = "%-$textlength".'s '."%$numlength"."d\n";

I don't see the point of all the dots. I think I would have used a straight double-quote interpolation:
    my $fmt = "%-${textlength}s %${numlength}d\n";
It seems clearer to my eye IMHO.

I like uniformity in the code ...

I like it too, and also the idea of reducing code to data. If I were to go all the way with this, I might write something like this (which also takes care of a common colon that's running through all the strings):

c:\@Work\Perl\monks>perl -wMstrict -le
"use List::Util qw(sum);
 ;;
 my $Sum = sum my ($FreqP, $FreqN, $FreqZ) = map { int rand 41600 } 0.
+.2;
 ;;
 my @rows = (
   ['Freq(Z+)', $FreqP], ['Freq(Z-)', $FreqN], ['Freq(0)', $FreqZ], ['
+Total', $Sum],
   );
 ;;
 my $txtwidth =  9;
 my $numwidth = 16;
 ;;
 my $fmt = qq{%-*s %*d \n};
 printf $fmt, $txtwidth, qq{$_->[0]:}, $numwidth, $_->[1] for @rows;
"
Freq(Z+):            25578
Freq(Z-):            39490
Freq(0):             13091
Total:               78159
[download]

The  $fmt string can now be generated/stored/retrieved entirely independently, data to be printed are pure data, etc.

But this is all probably overkill...