Need Mongoose js or Mongo db for a collection of Data

I have a MongoDB collection of documents. It has many fields. Each column has many possible values. I need to find out, each column has a distinct occurrence of a value and number of times of occurrence example: Let suppose field 1 has 10 possible values from A-J. How to find the distinct value with there counting like A: 5 B: 4: C:10 D:1 E:0 .. so on A:5 mean = 5 times 'A' present in whole collection I am able to do for a single column. But need help to do it for All the column in an optimized way.