nacka:
  s/(\d)(?=(\d{5})+(?!\d))/${1}-/g;
  substr($_, 17, 1, '<br>');

artist:
  s/((.){5})(?!$)/$1-/g;
  s/((.){17})\-/$1\<br\>/;

thezip:
s/(\d{5}) (\d{5}) (\d{5})
  (\d{5}) (\d{5}) (\d{5})
 /$1-$2-$3<br>$4-$5-$6/x;

nacka/artist hybrid:
  s/(\d)(?=(\d{5})+(?!\d))/$1-/g;
  s/((.){17})\-/$1\<br\>/;

artist/nacka hybrid:
  s/((.){5})(?!$)/$1-/g;
  substr($_, 17, 1, '<br>');