Creating a calculated field in Power BI - powerbi

Question

I have a tricky PowerBI problem that I'm hoping for some help with.
The data are as follows:
Product
Year
Purchases
'Book'
2020
24
'Book'
2021
15
'Book'
2022
10
'TV'
2020
42
'TV'
2021
48
'TV'
2022
33
'PC'
2020
130
'PC'
2021
115
'PC'
2022
170
I need help firstly making a calculated field that shows the percentage of growth/decline in each category year on year for the two most recent years (2021 and 2022 in this case). The change should be calculated as follows:
=(MostRecentYear - PreviousYear)/PreviousYear
2021 and 2022 can be specified if required, but would prefer to use MAX and MAX-1 to determine it so that I don't need to update code every year. If that's possible of course... It would also be great if the result can be expressed as a percentage and limited to one decimal place as per the table below.
Secondly, I need to include all these data in a matrix in the following format:
Product
2020
2021
2022
% Change
'Book'
24
15
10
-33.3%
'TV'
42
48
33
-31.3%
'PC'
130
115
170
47.8%
Thanks in advance.

Answer 1

Define the following three measures:
Total_Purchases =
SUM ( 'Table'[Purchases] )
% Change =
VAR Most_Recent_Year =
CALCULATE (
MAX ( 'Table'[Year] ),
ALL ( 'Table'[Year] )
)
VAR Previous_Year = Most_Recent_Year - 1
VAR Purchases_Most_Recent_Year =
CALCULATE (
[Total_Purchases],
'Table'[Year] = Most_Recent_Year
)
VAR Purchases_Previous_Year =
CALCULATE (
[Total_Purchases],
'Table'[Year] = Previous_Year
)
RETURN
DIVIDE (
Purchases_Most_Recent_Year - Purchases_Previous_Year,
Purchases_Previous_Year
)
2020 =
CALCULATE ( [Total_Purchases], 'Table'[Year] = 2020 )
Duplicate the last measure as required for other relevant years. Add all measures to a standard table visual.