how much does packing charge account for the total cost of the goods

翻译：
包装费用占总物资（中）的多少？

account for
v. 说明, 占, 解决, 得分

(1) To constitute the governing or primary factor:
导致，引起：构成决定性的或主要的因素：
Bad weather accounted for the long delay.
长期的延缓是因为坏天气

(2) To provide an explanation or justification:
做出解释，提出理由：
The suspect couldn't account for his time that night.
嫌疑犯不能说明那天晚上他的时间安排

商品(或货物)的包装费用占总成本的多少?