SELECT DISTINCT Entrant FROM driver WHERE Age  >=  20
What are the distinct entrant types of drivers aged 20 or older?
CREATE TABLE "driver" (
"Driver_ID" int,
"Driver_Name" text,
"Entrant" text,
"Constructor" text,
"Chassis" text,
"Engine" text,
"Age" int,
PRIMARY KEY ("Driver_ID")
);
CREATE TABLE "race" (
"Road" int,
"Driver_ID" int,
"Race_Name" text,
"Pole_Position" text,
"Fastest_Lap" text,
"Winning_driver" text,
"Winning_team" text,
"Report" text,
PRIMARY KEY ("Road"),
FOREIGN KEY (`Driver_ID`) REFERENCES `driver`(`Driver_ID`)
);
INSERT INTO  "driver" VALUES ("1","Ernst-Günther Burggaller","German Bugatti Team","Bugatti","Bugatti T35B","2.3 L8","18");
INSERT INTO  "race" VALUES ("2","1","Monterey Festival of Speed","James Hinchcliffe","Douglas Soares","James Hinchcliffe","Forsythe Pettit Racing","Report");