seriously vs you don't say

seriously

adv
  • Used to attempt to introduce a serious point in a less serious conversation. 

  • In a serious or literal manner. 

  • In an extreme or major way; majorly 

  • Used to call back to a previous point, in disbelief or for emphasis. 

  • Gravely; deeply; very much. 

you don't say

intj
  • Really?; no kidding!; is that so? (sometimes used sarcastically in response to the obvious) 

How often have the words seriously and you don't say occurred in a corpus of books? (source: Google Ngram Viewer )