CREATE TABLE table_42430 ("Season" TEXT, "Tier" FLOAT, "League" TEXT, "Postseason" TEXT, "European competitions" TEXT)

What is the average Tier when the postseason shows -, and the season is 2012 13?
SELECT AVG("Tier") FROM table_42430 WHERE "Postseason" = '–' AND "Season" = '2012–13'
SELECT AVG("Tier") FROM "table_42430" WHERE "Postseason" = '–' AND "Season" = '2012–13'