Here is a different approach using join and a couple of regular expressions. If the array was not already sorted you could just insert a sort { $a <=> $b } into the join line.

use strict;
use warnings;

my @yrArr = (
   1992,
   1994,
   1995,
   1997,
   1998,
   1999,
   2000,
   2002,
   2004,
   2005,
   2006,
   2007,
   2008,
   );

my $yrStr = join q{, }, @yrArr;

$yrStr =~ s{(\d+), (?=(\d+))}{ $2 - $1 == 1 ? qq{$1-} : qq{$1, } }eg;
$yrStr =~ s{(-\d+)+(?=-)}{}g;

print qq{$yrStr\n};
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The output.

1992, 1994-1995, 1997-2000, 2002, 2004-2008
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I hope this is useful.

Cheers,

JohnGG