CREATE TABLE table_15849 ("Order Year" CLOB, "Manufacturer" CLOB, "Model" CLOB, "Fleet Series  ( Quantity ) " CLOB, "Powertrain  ( Engine/Transmission ) " CLOB, "Fuel Propulsion" CLOB)

how many times is the fleet series (quantity) is 468-473 (6)?
SELECT COUNT("Order Year") FROM table_15849 WHERE "Fleet Series (Quantity)" = '468-473 (6)'
SELECT COUNT("Order Year") FROM "table_15849" WHERE "Fleet Series (Quantity)" = '468-473 (6)'