FORECAST function and Drop-down

[JCEurovision]

Good morning, everyone.

I would need some help because it involves two functions: FORECAST function and drop-down. I have attached the Excel spreadsheet containing the margins of victory of the winning candidate since 1900 (assuming the two-party system holds true). How can I use the drop-down menu to transpose some data to a new sheet? Also, I have planned to make a forecast of the next five elections, so how can I change the color of the upper and lower bound of the data once the FORECAST data is complete?

[JeteMc]

On Sheet2 cell C1 is populated using data validation with a source of A2:A57 on Sheet1.
The formula used to populate B3:B38 is: =IFERROR(1/(1/SUMPRODUCT((Sheet1!A$2:A$57=C$1)*(Sheet1!B$1:AF$1=A3)*(Sheet1!B$2:AF$57))),"")
The formula used to populate C33:C38 is: =IF(ISNUMBER(B33),"",FORECAST.ETS(A33,$B$3:$B32,$A$3:$A32,1))
Let us know if you have any questions.