Help with Qlik Sense Calculation

[ShellyG]

Dear all,

Thank you for always being responsive and helpful to my questions! 

I will need your help once again. I have a requirement to calculate forecast growth based on specific baselines. These baselines should be - last actual year, last 3 years and last three years. They should be all displayed in a line chart and a table. Just to make it more clear, I have actual data until 2019 and forecast data for 2020 to 2024. 

So far I managed to calculate the forecast growth based on the last actual year (in our case 2019) with the below formula:

(sum({<Year = {"$(=max( {<Source={'Main'}>}Year))"}>}Units)+sum(ForecastUnits))/$(=sum({<Year = {"$(=max( {<Source={'Main'}>}Year))"}>}Units))

Source 'Main' is the actual data and Source 'Forecast' is only regarding the forecast data. 

I cannot have a calendar as I don't have a date field and I am using directly the year, quarter and etc. fields that I have in my data. 

Any ideas on how to calculate the growth based on the lat 3 actual years?