muskeg vs swampland

muskeg

noun
  • A terrain composed of peat bog with tussocky meadow and woody vegetation including spruce. 

swampland

noun
  • Low-lying land that is regularly flooded; especially such land that is drier than a bog or a marsh. 

  • The set of effective low-energy physical theories that are not compatible with quantum gravity. 

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