croon vs national anthem

croon

noun
  • A soft or sentimental hum or song. 

verb
  • To make a continuous hollow moan, as cattle do when in pain. 

  • To say softly or gently 

  • To hum or sing softly or in a sentimental manner. 

  • To soothe by singing softly. 

national anthem

noun
  • The official song of a constituent state of a country. 

  • The official song of a nation or sovereign state, generally of a patriotic nature and played at events to celebrate or honor said state. 

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