How much does one spend a year on technical books?

I have always liked to buy technical books, most of which were translated from abroad, especially from XX Publishing House. People in the dormitory all said, "Are you very rich, I don't know how to answer this question? I always feel uncomfortable reading e-books. In fact, I have not carefully read some books from the beginning to the end, but I have always read them once. I have encountered problems and know where to read them, how much do you spend a year on purchasing technical books and conducting a survey? I hope you can cooperate and declare that there is no purpose, just curious. The answer format is as follows: X yuan/year, monthly income: Y yuan. Of course, if you do not want to disclose your salary information, you can leave it blank!