title: Calculate average time between an array of dates
body: <p>I have an array of objects which the app gets from a <code>WebService</code>, each object has a <code>createdTime</code> and objects are created randomly from 6 in the morning to midnight.</p>
  
  <p>I want to know what is the average time between each object creation.
   What is the best and most efficient way to implement it?</p>
  
  <p>The dates are in this format: <code>"CreatedTime": "2019-02-18T22:06:30.523</code>"</p>