elbow grease vs slogging

elbow grease

noun
  • Effort or hard work, especially physical work involving repeated motion of the forearm, such as scrubbing. 

slogging

noun
  • An act or an instance of slogging or working laboriously. 

  • A beating or thrashing. 

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