Hi,
I'd go with split:

#!/usr/bin/perl

use strict;
use warnings;

my @Read = <DATA>;

for (@Read){
  next unless /^Number-/;
  chomp;
  $_ =~ s/Number-//g;
  my @numbers = split(/,/);
  print join("\n", @numbers),"\n";
}

__DATA__
Number:
Number-1999-1011
----------------------------------------
Number:
Number-1999-0696
----------------------------------------
Number:
Number-1999-0833,Number-2004-0786,Number-2004-0747,Number-2004-075,Num
+ber-2004-0748,Number-2004-0809
----------------------------------------
Number:
Number-2000-1209
----------------------------------------
[download]

output:

1999-1011
1999-0696
1999-0833
2004-0786
2004-0747
2004-075
2004-0748
2004-0809
2000-1209
[download]

Regards,
svenXY

update: I personally prefer the solution moritz++ offered above. It's also more regex-like - as was asked for in the OP.