Ministry of Education’s Regulations Governing the Establishment of the National Professorship Article 4

The annual quota for approved National Chair Professorships shall be limited to thirteen which shall be allocated among the disciplinary categories specified in Article 3, Paragraph 3, Subparagraph 1. The Humanities and Arts category and the Social Sciences category shall each be allocated two, and the remaining categories shall each be allocated three.
中文原文 教育部設置國家講座辦法第4條
國家講座主持人每年核准名額,以十三名為限,依第三條第三項第一款所定類科分配名額,除人文及藝術、社會科學類科各分配二名外,其餘三類科各分配三名。

English translation for reference only; the Chinese text prevails. Not legal advice.