CREATE TABLE orders
(
  persistent_key_str character varying,
  ord_id character varying(50),
  ord_submitted_date date,
  item_sku_id character varying(50),
  item_extended_actual_price_amt numeric(18,2)
);

INSERT INTO orders VALUES ('01120736182','ORD6266073','2010-12-08','100856-01',39.90);
INSERT INTO orders   VALUES('01120736182','ORD33997609','2011-11-23','100265-01',49.99);
 INSERT INTO orders VALUES('01120736182','ORD33997609','2011-11-23','200020-01',29.99);
 INSERT INTO orders VALUES('01120736182','ORD33997609','2011-11-23','100817-01',44.99);
 INSERT INTO orders VALUES('01120736182','ORD89267964','2012-12-05','200251-01',79.99);
 INSERT INTO orders VALUES('01120736182','ORD89267964','2012-12-05','200269-01',59.99);
 INSERT INTO orders VALUES('01011679971','ORD89332495','2012-12-05','200102-01',169.99);
INSERT INTO orders VALUES('01120736182','ORD89267964','2012-12-05','100907-01',89.99);
 INSERT INTO orders VALUES('01120736182','ORD89267964','2012-12-05','200840-01',129.99);
 INSERT INTO orders VALUES('01120736182','ORD125155068','2013-07-27','201443-01',199.99);
 INSERT INTO orders VALUES('01120736182','ORD167230815','2014-06-05','200141-01',59.99);
 INSERT INTO orders VALUES('01011679971','ORD174927624','2014-08-16','201395-01',89.99);
 INSERT into orders values('01000217334','ORD92524479','2012-12-20','200021-01',29.99);
INSERT into orders values('01000217334','ORD95698491','2013-01-08','200021-01',19.99);
INSERT into orders values('01000217334','ORD90683621','2012-12-12','200021-01',29.990);
INSERT into orders values('01000217334','ORD92524479','2012-12-20','200560-01',29.99);
INSERT into orders values('01000217334','ORD145035525','2013-12-09','200972-01',49.99);
INSERT into orders values('01000217334','ORD145035525','2013-12-09','100436-01',39.99);
INSERT into orders values('01000217334','ORD90683374','2012-12-12','200284-01',39.99);
INSERT into orders values('01000217334','ORD139437285','2013-11-07','201794-01',134.99);
INSERT into orders values('01000827006','W02238550001','2010-06-11','HL 101077',349.000);
INSERT into orders values('01000827006','W01738200001','2009-12-10','EL 100310 BLK',119.96);
INSERT into orders values('01000954259','P00444170001','2009-12-03','PC 100455 BRN',389.99);
INSERT into orders values('01002319116','W02242430001','2010-06-12','TR 100966',35.99);
INSERT into orders values('01002319116','W02242430002','2010-06-12','EL 100985',99.99);
INSERT into orders values('01002319116','P00532470001','2010-05-04','HO 100482',49.99);

select
    g.order_date as "Ordered",
    count(distinct o.persistent_key_str) as "customers"
from
    generate_series(
        (select min(ord_submitted_date) from orders),
        (select max(ord_submitted_date) from orders),
        '1 day'
    ) g (order_date)

    left join
    orders o on o.ord_submitted_date between g.order_date - interval '364 days' and g.order_date
    WHERE extract(year from ord_submitted_date) <= '2009'

group by 1
order by 1

Ordered      Customers
2009-12-03   1
2009-12-10   1