CREATE TABLE table_73700 ("Outcome" TEXT, "Year" FLOAT, "Championship" TEXT, "Surface" TEXT, "Partner" TEXT, "Opponents" TEXT, "Score" TEXT)

When Australian open is the championship what is the lowest year?
SELECT MIN("Year") FROM table_73700 WHERE "Championship" = 'Australian Open'
SELECT MIN("Year") FROM "table_73700" WHERE "Championship" = 'Australian Open'