(FNR <= 5) {
	print ((FILENAME   ": ")   $0);
}

cou-en.data: USSR	8649	275	Asia
cou-en.data: Canada	3852	25	North America
cou-en.data: China	3705	1032	Asia
cou-en.data: USA	3615	237	North America
cou-en.data: Brazil	3286	134	South America