right as rain vs rigorous

right as rain

adj
  • Correct; factually accurate. 

  • Very good; all in order; healthy. 

rigorous

adj
  • Showing, causing, or favoring rigour/rigor; scrupulously accurate or strict; thorough. 

  • Severe; intense. 

How often have the words right as rain and rigorous occurred in a corpus of books? (source: Google Ngram Viewer )