CREATE TABLE table_3523 ("Week #" TEXT, "Theme" TEXT, "Song choice" TEXT, "Original artist" TEXT, "Order #" TEXT, "Result" TEXT)

How many original artists were there for the Group Performance?
SELECT COUNT("Original artist") FROM table_3523 WHERE "Theme" = 'Group Performance'
SELECT COUNT("Original artist") FROM "table_3523" WHERE "Theme" = 'Group Performance'