esprit de corps vs logrolling

esprit de corps

noun
  • A shared spirit of comradeship, enthusiasm, and devotion to a cause among the members of a group, for example of a military unit. 

logrolling

noun
  • Mutual recommendation of friends' or colleagues' services or products, such as book recommendations in literary reviews. 

  • The act of balancing on a log floating on a river to guide it downstream, often involving rolling it using one's feet; birling. 

  • The rolling of logs from one place to another; an occasion when people meet to help each other roll logs. 

  • A concerted effort to push forward mutually advantageous legislative agendas by combining two items, either or both of which might fail on its own, into a single bill that is more likely to pass. 

  • A sport in which two people balance on a log floating in a body of water, each one aiming to cause the opponent to fall off by rolling or kicking the log. 

How often have the words esprit de corps and logrolling occurred in a corpus of books? (source: Google Ngram Viewer )