CREATE TABLE table_19864 ("Outcome" TEXT, "Year" FLOAT, "Championship" TEXT, "Surface" TEXT, "Partner" TEXT, "Opponents in the final" TEXT, "Score in the final" TEXT)

What year was the most recent US Open championship?
SELECT MAX("Year") FROM table_19864 WHERE "Championship" = 'US Open'
SELECT MAX("Year") FROM "table_19864" WHERE "Championship" = 'US Open'