CREATE TABLE table_21562 ("Team" TEXT, "Outgoing manager" TEXT, "Manner of departure" TEXT, "Date of vacancy" TEXT, "Replaced by" TEXT, "Date of appointment" TEXT)

How many vacancies happened on 25 May?
SELECT COUNT("Manner of departure") FROM table_21562 WHERE "Date of vacancy" = '25 May'
SELECT COUNT("Manner of departure") FROM "table_21562" WHERE "Date of vacancy" = '25 May'