CREATE TABLE table_18067 ("No. in series" FLOAT, "No. in season" FLOAT, "Title" TEXT, "Directed by" TEXT, "Written by" TEXT, "Original air date" TEXT)

How many episodes have been directed by David Duchovny?
SELECT COUNT("Title") FROM table_18067 WHERE "Directed by" = 'David Duchovny'
SELECT COUNT("Title") FROM "table_18067" WHERE "Directed by" = 'David Duchovny'