second class vs voicemail

second class

noun
  • A class of postage with delivery times slower than first class. 

  • A class of travel, inferior to first class. 

  • The second-lowest rank in the Boy Scouts of America, between tenderfoot and first class. 

voicemail

noun
  • A computerized interactive system for storing, processing and reproducing verbal messages left through a conventional telephone network. 

  • An individual message on such a system. 

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