ideogram vs semantogram

ideogram

noun
  • A picture or symbol which represents the idea of something without indicating the sequence of sounds used to pronounce it. Examples include digits, traffic signs, and graphic symbols such as @. 

semantogram

noun
  • A symbol used solely for meaning, as when logographic Chinese symbols are used to represent the meaning of native Japanese words. 

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