ECTS Users' Guide
The EC has given much attention to Grade Conversion and Egracons in its new 2015 ECTS users' Guide
Here is the extract on grade distribution and grade conversion
Here is Annex 2 with elaborated examples of conversion
The full version can be found here. The website can be found at: http://ec.europa.eu/education/ects/users-guide/index_en.htm and a video on grading tables here