earn vs rack up

earn

verb
  • To gain (success, reward, recognition) through applied effort or work. 

  • To cause (someone) to receive payment or reward. 

  • To achieve by being worthy of. 

  • To receive payment for work. 

rack up

verb
  • to gain (points etc.; in a game or sport), to accumulate 

  • to arrange in a rack 

  • to acquire, to gather together. 

  • to defeat severely, to thrash 

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