at a premium vs insufficient

at a premium

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

  • Scarce, in short supply. 

  • Above par value. 

insufficient

adj
  • Not sufficient; lacking competent power or ability; unqualified, unequal, unfit. 

  • Not sufficient; of a type or kind that does not suffice, that does not satisfy requirements or needs. 

det
  • An inadequate quantity of; not enough. 

  • A quantity (of something) that is less than is needed. 

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