use List::Util qw( sum );

my $groups_hr = find_groups { $_->{'name'} } @rows;

for my $k ( sort keys %$groups_hr )
{
	my $avg = sum( map { $_->{'score'} } @{$groups_hr->{$k}} ) / @{$groups_hr->{$k}};
	print "$k\t$avg\n";
}