Name the party with first elected more than 1999 and position of supervisor for john foust
CREATE TABLE "county_board_of_supervisors" (
  "position" text,
  "name" text,
  "party" text,
  "first_elected" real,
  "district" text
);
SELECT "party" FROM "county_board_of_supervisors" WHERE "first_elected">1999 AND "position"='supervisor' AND "name"='john foust';