l_shipmode	max(l_shipdate)	min(l_shipdate)
AIR	1998-11-29	1992-01-02
FOB	1998-11-28	1992-01-04
MAIL	1998-12-01	1992-01-03
RAIL	1998-11-30	1992-01-03
REG AIR	1998-11-28	1992-01-02
SHIP	1998-12-01	1992-01-02
TRUCK	1998-12-01	1992-01-03