How many motorcycles have been ordered in 2004?
Motorcycles refer to productLine = 'motorcycles'; ordered in 2004 refers to year(orderDate) = 2004;
SELECT SUM(t2.quantityOrdered) FROM orders AS t1 INNER JOIN orderdetails AS t2 ON t1.orderNumber = t2.orderNumber INNER JOIN products AS t3 ON t2.productCode = t3.productCode WHERE t3.productLine = 'motorcycles' AND STRFTIME('%Y', t1.orderDate) = '2004'