obtain vs rack up

obtain

verb
  • To get hold of; to gain possession of, to procure; to acquire, in any way. 

rack up

verb
  • to acquire, to gather together. 

  • to arrange in a rack 

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

  • to defeat severely, to thrash 

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