Rubric to Percentage Conversion Table

For some time, I have been puzzling over using rubrics to score skills assessments such as essays, projects, presentations, etc. Simply entering rubric scores into a grading program produces unwanted results that do not accurately reflect a letter grade conversion of rubric scores. I could go into the mathematical details, but if you are interested check this article or this one. I am not satisfied by the specific conversions offered by either of the previous sources but the descriptions of the rubric to percentage problem are adequate enough to justify the need for a conversion tool. Below is a chart I created that converts a 5pt rubric (0-4) into grade percents. Click on the image for better quality.
There are some inherent compromises in these scores, but I feel they adequately represent the various levels of proficiency I expect when grading. I have just begun implementing this tool in my grading and so far I am liking the results.

If you decide to use this please post feedback on how it works for you.