欧洲的飞机制造业得到好几个国家政府的资助。根据估计，这些资助相当于每架飞机售价的20%。也就是说，1架卖5000万美元的飞机，其成本可能为6000万美元，成本与售价的差额就由欧洲各国政府来弥补。同时，一架“欧洲”飞机售价的约一半是从其他国家(包括美国)购买的零部件成本。如果这些估计成立，请问欧洲飞机制造商得到的有效保护率为多少? The aircraft industry in Europe receives aid from several governments，according to some estimates，equal to 20 percent of the purchase price of each aircraft．For example，an airplane that sells for ＄50 million may have cost ＄60 million to produce，with the difference made up by European governments．At the same time．approximately half the purchase price of a“European”aircraft represents the cost of components purchased from other countries(including the United States)．If these estimates are correct，what is the effective rate of protection received by European aircraft producers?