CREATE TABLE table_19638 ("Position" FLOAT, "Race number" TEXT, "Sail number" TEXT, "Yacht" TEXT, "State/country" TEXT, "Yacht type" TEXT, "LOA  ( Metres ) " TEXT, "Skipper" TEXT, "Elapsed time d:hh:mm:ss" TEXT)

How many different skippers of the yacht City Index Leopard?
SELECT COUNT("Skipper") FROM table_19638 WHERE "Yacht" = 'City Index Leopard'
SELECT COUNT("Skipper") FROM "table_19638" WHERE "Yacht" = 'City Index Leopard'