For %total please use go through this thread hope this will help you
There is another way to achieve by using table calculation:-
SUM([Number of Records]) / TOTAL(SUM([Number of Records]))
If still you face any problem please upload your tableau file and give us what exact outcome you want to achieve either in a excel or in a picture
I'm not looking to find a % of the total across all years combined, i'm looking to find a % of total for each individual year.