How to count running months of a specific year? - excel

Question

I'm currently struggling with calculating the running months depending on the year. I have the following table:
Received Month Received Year
Feb 2018
Feb 2018
Mar 2018
... ...
Nov 2018
Nov 2018
Dec 2018
Dec 2018
Jan 2019
Jan 2019
Feb 2019
I was using this formula to count the # of unique months (running months in 1 single cell [C1]);
=SUMPRODUCT(1/(COUNTIF(KAIZEN_Table[Received Month],KAIZEN_Table[Received Month])))
This was working great in 2018, it gave me 11 (Feb - Dec).
I have to add a filter that also checks if the year is 2019. I can't remove 2018 in the table because the operators are still using the 2018 lines. The filter is just here to set a KPI for 2019.
For some reason I can't figure out how to add the year. I tried;
=SUMPRODUCT(1/(COUNTIFS(KAIZEN_Table[Received Month],KAIZEN_Table[Received Month],KAIZEN_Table[Received Year], "2019")))
This is just giving me a 0.
Any suggestions on this? VBA code is also fine.
Edit: After extensive googling I found a working formula, for whoever might be interested in this.
=SUM(IF(FREQUENCY(IF(tbl[Year]=2019,MATCH(tbl[Month],tbl[Month],0)),ROW(tbl[Month])-ROW($L$5)+1),1))
L5 = First row of tbl[Month]

Answer 1

I have my data in A1:B14, the formula I've used is an array one
=SUM(1/(COUNTIFS($A$1:$A$14,$A$1:$A$14,$B$1:$B$14,$B$1:$B$14)))
however,
=SUMPRODUCT(1/(COUNTIFS($A$1:$A$14,$A$1:$A$14,$B$1:$B$14,$B$1:$B$14)))
would suffice
To do a particular year, you could do something like this
=SUM(($B$1:$B$14=2019)*(1/COUNTIFS($A$1:$A$14,$A$1:$A$14,$B$1:$B$14,B1:B14)))

Answer 2

Another approach is to use a Pivot Table.
On the Create Pivot Table dialog, select to Add this data to the Data Model
If you do this, you will note that one of the options in the Value Field Settings will be Distinct Count
Drag Received Year to the Rows Column; Received Month to the Values column, and select Distinct Count for the Value Field Setting