Guoyu vs Putonghua

Guoyu

name
  • The standardized spoken Chinese language, also referred to as Standard Mandarin. The term remains in common use in the Republic of China (Taiwan) and colloquially in Hong Kong (along with Putonghua). In mainland China, Guoyu or Taiwan Guoyu is used to refer to Taiwanese Mandarin (standard), as opposed to mainland standard Mandarin. 

  • The language the Emperor of China spoke. 

Putonghua

name
  • Standard Mandarin, the official language of the People's Republic of China; the state-designated national speech of the Han nationality using Beijing pronunciation as the standard pronunciation, Beijing speech as the basic dialect, and the model writing of the modern vernacular prose as the norm for grammar. 

How often have the words Guoyu and Putonghua occurred in a corpus of books? (source: Google Ngram Viewer )