my $col_width = 20;
my @keys      = sort keys %data;
my $p_format  = join(" " => ("%${col_width}s") x @keys) . "\n";

## $p_format would be "%20s %20s %20s ... %20s\n", so the columns will
## line up even if the data strings are different sizes

printf $p_format, @keys;

my $i = 0;
LOOP: {
    ## important part: pull out the ith entry in each array
    my @ith_data = map { $data{$_}[$i] || "" } @keys;

    ## you mentioned the data strings end in \n
    chomp @ith_data; 

    printf $p_format, @ith_data;

    $i++;

    ## loop again if any array has elements left
    for (@keys) {
        redo LOOP if exists $data{$_}[$i];
    }
}