The Fields History Helper plugin helps you in setting up field history on standard and custom objects:

The plugin is injected inside the Field History page for any Salesforce object and can be used to:

• Display a counter for all the selected fields (so you know exactly how many fields are you tracking)
• Use the Analyze Fields button to:
  • Show Field API Names
  • Query the last 1000 records created on the org and calculates the % of records where the field is filled in and the % of variance (i.e. the % of records with different values)

Read the Options section to enable or disable this feature.