Unexpected error for input string: "%" message when importing custom market assumptions

Issue: 

When I go to Preferences > Market Assumptions > click Create > click Load from File and then attempt to load our market assumptions and correlation coefficient files, I get some variant of the following error message stating, an unexpected error has occurred... ...for input string: "2.51%". The percentage may be different but the error is the same. 

Cause: 

Check your market assumptions and correlation coefficient files and verify that it adheres to the following formatting requirements, as detailed in our Market Assumptions Customisation Guide

The usual culprit is the formatting of percentages. 

1. The market assumptions file must be in a comma-separated value (.csv) format.
2.  
Returns must be in decimal format, not a percentage format - e.g. 6.2% must be entered as .062 in this file, not as 6.2 or 6.2%.
3.  Asset classes, which serve as the column headings, must be formatted in all caps with underscores used to represent spaces.
4.  CASH is a required asset class with all others being adviser defined.

5.  There is no maximum limit on the number of asset classes; however, over fifteen classes may affect their display in the Voyant user interface.