Calculated measure kpi

I asked this question before, but I didn't explain it correctly.
so I have a table ( "TABLE 1") that has 4 columns, I wanted to create a kpi using Line and grouped column chart.

the table contains the target of different SBU for different months of the year 2020.

I created another table with the same column names, but the SBU is empty along with the target. (TABLE 2)

Therefore, in my line and grouped column chart when no SBU is selected should display the values in Table 2 and when SBU is selected it should show the maximum value of that particular SBU during all months.

but I don't know how to create a measure for this particular problem. In the previous view when SBU is not selected it is assumed to show 94.40% for the month of January of TABLE 2, instead of that it is showing 94.20% because it is taking the average of all SBU for the month of JANUARY of TABLE 1