Report which would give us info that fields on object (say contact) are filled or Not

Summary:

We need to come up with report which would give us information that fields present on object (say contact) are filled in or not considering all records.

For example, Email field on Contact, On how many records this field is updated ? say 80% or 60%

Can you guide is which subject area or what feature we can use to achieve this ?

Content (required):

We need to come up with report which would give us information that fields present on object (say contact) are filled in or not considering all records.

For example, Email field on Contact, On how many records this field is updated ? say 80% or 60%