This is happening because you're not dereferencing an array.

Maybe something like:

use strict;
use warnings;
use Data::Dumper;

# This will give you a clearer idea of what you data actually looks li
+ke
print Dumper($AoH); 

# This assumes that $data is an index (integer)
my $year = $AoH->[$data]{'YEAR'};
[download]

If this doesn't work for you, post the contents of the Data::Dumper output, and we'll talk some more.