Hello excel gurus.

I need help! I know too little to put everything i need together.

I have 4 worksheets with lists of codes (column A) and the number of times they were used per month (column D-CI).
Each worksheets have the same codes but used byt 4 different people. as of now there are about 71 codes but this number can change every month when new data is added.

I want to create a end user lookup function that creates a graph of the code searched for. It should make a line graph with 4 lines over the span of months for every code that is searched. The problem is the data on 4 spreadsheets is updated every month and the number of codes can change; so is there a way to have this accounted for. I also dont konw how to make this presentable for an end user.
I have attempted very basic approaches using macros and vlookup but those are only baby steps.

Thanks in advance for any advice. - XLrookie