Answer:

Update: It is now possible to count unique distinct values in a Pivot Table. You need Excel 2013 or a later version.

I don´t think it is possible to count unique values in a pivot table unless you add another column to your table or use VBA:  Improve your Excel Pivot Table to count unique values or items

Formula in D3:

Copy cell D3 (Ctrl + c). Paste (Ctrl+ v) on cell range D4:D17.

Setup pivot table

1. Press with left mouse button on and drag Array formula to Row Labels
2. Press with left mouse button on and drag Count to Values

How the formula in cell D3 works

Step 1 - Construct the COUNTIF function

COUNTIF(range,criteria) counts the number of cells within a range that meet the given condition.

Select cell D3.

Type =COUNTIF(

Select cell range C3:C17

Press F4. You have now created absolute cell references to cell range C3:C17.
=COUNTIF($C$3:$C$17

Now create a relativ cell reference to cell C3.
=COUNTIF($C$3:$C$17, C3)

=COUNTIF($C$3:$C$17, C3)

becomes

=COUNTIF({"AA"; "AA"; "AA"; "BB"; "BB"; "BB"; "BB"; "BB"; "BB"; "BB"; "BB"; "CC"; "CC"; "CC"; "CC"}, "AA")

and returns 3. There are three AA in the array.

Step 2 - Divide 1 with the number of counted values

=1/COUNTIF($C$3:$C$17, C3)

becomes

=1/3

and returns

0.333333333333333 in cell D3.

Count values in a pivot table using an Excel defined table as a data source

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