at a premium vs frequent

at a premium

prep
  • At a high, or higher than expected, price. 

  • Scarce, in short supply. 

  • Above par value. 

frequent

adj
  • Done or occurring often; common. 

  • Occurring at short intervals. 

  • Addicted to any course of conduct; inclined to indulge in any practice; habitual; persistent. 

verb
  • To visit often. 

How often have the words at a premium and frequent occurred in a corpus of books? (source: Google Ngram Viewer )