expectation vs should

expectation

noun
  • That which is expected or looked for. 

  • The act or state of expecting or looking forward to an event as about to happen. 

  • The value of any chance (as the prospect of prize or property) which depends upon some contingent event. 

  • The first moment; the long-run average value of a variable over many independent repetitions of an experiment. 

  • The arithmetic mean. 

  • The leaving of a disease principally to the efforts of nature to effect a cure. 

  • The prospect of the future; grounds upon which something excellent is expected to occur; prospect of anything good to come, especially of property or rank. 

should

noun
  • Something that ought to be the case as opposed to already being the case. 

verb
  • Will be likely to (become or do something); indicates a degree of possibility or probability that the stated thing will happen or be true in the future. 

  • Indicates that something is expected to have happened or to be the case now. 

  • Used to express a conditional outcome. 

  • With verbs such as 'see' or 'hear', usually in the second person, used to point out something remarkable in either a good or bad way. 

  • To make a statement of what ought to be true, as opposed to reality. 

  • Used to impart a tentative, conjectural or polite nuance. 

  • Used to express what the speaker would do in another person's situation, as a means of giving a suggestion or recommendation. 

  • Simple past tense of shall. 

  • In questions, asks what is correct, proper, desirable, etc. 

  • Used to issue an instruction (traditionally seen as carrying less force of authority than alternatives such as 'shall' or 'must'). 

  • Used to give advice or opinion that an action is, or would have been, beneficial or desirable. 

  • Used to form a variant of the present subjunctive, expressing a state or action that is hypothetical, potential, mandated, etc. 

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