S vs protein

S

character
  • The nineteenth letter of the English alphabet, called ess and written in the Latin script. 

name
  • An axiomatic set theory, developed by logician George Boolos, in which several of the axioms of ZF are derivable as theorems. 

protein

noun
  • A food rich in protein, often a meat or meat substitute. 

  • Any of numerous large, complex naturally-produced molecules composed of one or more long chains of amino acids, in which the amino acid groups are held together by peptide bonds. 

  • One of three major classes of food or source of food energy (4 kcal/gram) abundant in animal-derived foods (i.e. meat) and some vegetables, such as legumes. 

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