Formatting data for stacked chart

Hi,

I am attempting to create a 100% stacked column out of the data shown. Ideally, it will have average satisfaction on the y-axis, the year on the x-axis, and whether or not they are a union member shown through colours. However, I am struggling with how to format the data in order to do this. There are over 50,000 rows of data. Any help would be much appreciated, thanks.