CREATE TABLE table_33828 ("Season" TEXT, "Episodes" FLOAT, "First airdate" TEXT, "Last airdate" TEXT, "Nielsen ranking" TEXT)

Which season last aired on May 6, 1987?
SELECT "Season" FROM table_33828 WHERE "Last airdate" = 'may 6, 1987'
SELECT "Season" FROM "table_33828" WHERE "Last airdate" = 'may 6, 1987'