if(not defined $institution) {
    $institution_table{ unaffiliated }++;
} else {
    $institution_table{ $_ }++
        for grep { $institution eq $_ } ( $hospital1 $hospital2 );
}

##</code><code>##

$institution_table{$_}->{"fortyfive_fifty"} ++ 
        if 45 > $age and $age <= 50;