CREATE TABLE table_62543 ("Time" TEXT, "Show Name" TEXT, "Local/Networked" TEXT, "Ad Freq" TEXT, "News Freq" TEXT)

How often are there ads during American Top 40?
SELECT "Ad Freq" FROM table_62543 WHERE "Show Name" = 'american top 40'
SELECT "Ad Freq" FROM "table_62543" WHERE "Show Name" = 'american top 40'