Complex sentence: The fourth is the Republic of Ireland, with 8 songs, followed Jamaica (7 songs; 4 by Bob Marley), Australia (3 songs; 2 by AC/DC), Sweden (1 song; "Dancing Queen" by ABBA).
Split into simpler sentences: The fourth is the Republic of Ireland, with 8 songs. Then Jamaica (7 songs; 4 by Bob Marley), Australia (3 songs; 2 by the AC/DC), Sweden (1 song; "Dancing Queen" by ABBA).