Unable to symbolize CSV data by quantity

Description

When symbolizing a numeric field in ArcMap in the Layer Properties dialog box on the Symbology tab under Quantities and under Graduated colors, a blank Field Value drop-down list results from generating data using the CSV file.

Cause

String fields cannot be symbolized. Symbolizing by quantity requires a numeric field.

Note:
In the Symbology tab, the Graduated colors option is often used to symbolize the fill of a polygon with quantities. Quantities are typically used with quantitative data or numeric fields, while categories are typically used with qualitative data, string fields, or text fields. 

Solution or Workaround

1. Add the CSV file into ArcMap.
2. In the Table of Contents, right-click the CSV file, and select Data > Export...
   
   
3. Save the CSV file. For 'Save as type:', select Text File, and change the extension to .csv instead of .txt. Click Save > OK.
   
   
4. Using Windows Explorer, browse to where the CSV file is saved. A schema.ini file is created.
   
   
5. Using Notepad, right-click the schema.ini file, and select Edit.
6. Change the text values to Double.
   
   Once completed, users may select the Double field in the drop-down list when symbolizing in the Symbology tab.