Mandarin Chinese vs Standard Mandarin

Mandarin Chinese

noun
  • A group of related Chinese dialects spoken across most of northern and southwestern China. 

  • Standard Mandarin. 

Standard Mandarin

noun
  • The official language of the People's Republic of China and the Republic of China, based on the Beijing dialect of Mandarin and accepted as a lingua franca for Han communities worldwide. 

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