Among the shipments for Downey, how many shipments were shipped to California in 2016?
"Downey" is the city_name; 'California' is the state, whose abbreviation is CA; in 2016 refers to year(ship_date) = 2016,
SELECT COUNT(*) FROM shipment AS T1 INNER JOIN city AS T2 ON T1.city_id = T2.city_id INNER JOIN customer AS T3 ON T3.cust_id = T1.cust_id WHERE T2.city_name = 'Downey' AND STRFTIME('%Y', T1.ship_date) = '2016' AND T3.state = 'CA'