sub count {
	my ($data, $fields) = @_;
	$fields = [$fields] unless ref $fields;
	my $count = {};
	_dive( $count, $_, @$fields ) for @$data;
	return $count;
}
sub _dive {
	my ($ref, $obj, @path) = @_;
	my $targ = \$ref->{ $obj->{ shift @path } };
	if (!@path) { $$targ++; return $ref }
	$$targ = _dive( $$targ, $obj, @path );
}

print Dumper( count(\@array_of_objects, 'sex') );
print Dumper( count(\@array_of_objects,
	['sex','occupation']) );