Why is the annual patent fee increasing?

More and more annual fees play the role of an economic lever, because patent rights are exclusive and exclusive. Only when the patentee who has obtained the patent right considers that the economic benefits obtained by his exclusive right are greater than the expenses such as annual fees, is he willing to pay more and more annual fees to protect his exclusive right from being used by others, which is the protection for the patentee; If the patentee thinks that he can't make much money from this thing, and it's not enough to pay the annual fee, he will give up this patent and this exclusive right, so that people all over the world can use it, thus promoting scientific and technological progress and economic and social development, which is also the purpose of designating the patent law.