I still don't understand what your input data might look like, but is this closer to your output example?

#!/usr/bin/perl -w

use strict;
use warnings;

my ( $county, $year_x, $yr_tot, $production );

my $result = &make_table;
print $result;


sub make_table {
   open YEARLY, '>', \$production; 
   print YEARLY "             2001     2002     2003     2004 \n";
   while ( <DATA> ) {
      ( $county, $year_x, $yr_tot ) = split ' ', $_;
      if ( $year_x eq "1" || "2" || "3" || "4" ) {
         $year_x += $yr_tot;
         write YEARLY;
      }
   }
   return $production;
}


format YEARLY =
@<<<<<<<<    @<<<<
$county,     $year_x
.

close YEARLY;


__DATA__
McMahon 1 9000
McHardy 2 8000
Moonlit 3 7000
Murphie 4 6000
[download]

Returns:

             2001     2002     2003     2004 
McMahon      9001
McHardy      8002
Moonlit      7003
Murphie      6004
[download]

No writing to a disk file until you need to...