对PowerBI和DAX中缺少数据的度量进行平均

我试图绕过DAX奋斗。我有一个PowerBI矩阵，我需要在其中计算度量的平均值。该度量是“人口百分比”，从表面上看，它似乎完全符合预期。

它在两个级别的顶部矩阵中正确计算，并且在底部表格中正确汇总。

例如，我以红色突出显示了“ A3”的计算顺序

为了记录，人口百分比设置为

% of Population = sum(Data[Value])/sum('Level'[Population])

当我在“国家/地区”上进行过滤并仅选择“国家2”时会出现问题

Country 2 does not have data for "D13". Although the Values sum up correctly (170), the Sum of the Population includes the 300 from the missing D13 row making a total of 600 and the '% population' of 28.33% (instead of 170 / 300 = 57%)

I am happy to turn off the group totals in the top grid so that the 28.33 does not show; so my real problem is actually with the bottom grid.

I think I need a new measure to be displayed in the bottom grid. I think it simply needs to sum up the values and divide by the sum of the populations - but only when the value is present. How do I do that?

Or am I totally on the wrong track and there is an obvious answer that I am missing?

The PowerBI file can be downloaded from here

Thanks in advance.