use Text::xSV;
my $csvI = new Text::xSV;
my $csvO = new Text::xSV;

$csvI->open_file("country.txt");
$_->set_sep("\t") for ($csvI, $csvO);
$csvI->read_header();

my @F;
foreach( keys(%{$csvI->{field_pos}}) ){
    $F[$csvI->{field_pos}->{$_}] = $_;
}

$csvO->set_header(\@F);
$csvO->print_header();
while ($csvI->get_row()) {
    my %F = $csvI->extract_hash();
#Do stuff here
    $F{EFM2}*=1.1;
    $csvO->print_data(%F);
}