Line chart not displaying all percentages for a measure

[Anonymous]

Hi there, I hope I have posted this in the correct place. 

I have been tasked to create a stats report for an awarding organisation. They would like me to put together a line graph that compares:

1. A exam centres marks out of 100 as a percentage for each value, over all time. e.g. 3.7% scored 67/100, 4.8% scored 84/100 etc
2. An examiners marking out of a 100, which can be filtered by a date range slider and the percentage line will adjust accordingly

Context: This report will enable our moderators to compare how an examiner has been performing in the past month or two, against the centres performance over all time. This will mean that our moderators will be able to see whether an examiner is marking too harshly or too leniently against the centres overall average.

To calculate the percentage of all marks out of 100 for a given centre, I have implemented the two following measures:

TotalExamsAtCentre =
CALCULATE (
    DISTINCTCOUNT ( 'ExaminerAndCentre'[ResultId] ),
    ALL ( 'ExaminerAndCentre'[Result Added Date] ),
    ALL ( 'ExaminerAndCentre'[Examiner] )
)

CentrePercentage =
[TotalExamsAtCentre]
    / CALCULATE (
        [TotalExamsAtCentre],
        ALL ( 'ExaminerAndCentre'[Mark of 100] ),
        ALL ( 'ExaminerAndCentre'[Result Added Date] )
    )

The ALL [Result Added Date] filter is important in these expressions as I don't want the date range slider to be affecting the stats, as they need to be for all time. 

For the examiner i have implemented two similar measures:

TotalExams =
COUNT ( ExaminerAndCentre[ResultId] )

ExaminerPercentage =
[TotalExams]
    / CALCULATE ( [TotalExams], ALL ( 'ExaminerAndCentre'[Mark of 100] ) )

These measures are this way, as the percentage will vary depending on what slicer filters have been applied. 

Here is a screen shot of my current report

 The examiner line is perfectly correct, the percentage adds up to 100. However, the centre line does not. This is because the line graph only creates a matching point where one appears in the Examiner line, so there are a lot of missing values in the blue line and I am struggling to find a solution for this. This issue happens when the Result Added Date Slicer has been reduced so that the examiner has only marked a few exams, and a limited number of Marks out of 100 are available.

Feel free to download the report here - 

https://rockschoolproduction.blob.core.windows.net/public/Examiner%20and%20Centre%20Statistics%20Exa...

Thank you for taking the time to read this and for any help you can give. This is my first time posting on here, and I hope this post is informative to my issue. 

[lbendlin]

Tell your customer that a line chart is not appropriate in this scenario.