How to make a sheet that only shows the last x entries of another sheet

Hello,

What I am trying to do is track overtime hours taken for each department in our company. I have a sheet set up where our HR rep can submit a form for each week's value, but I need to display this in a chart, and that is where I am running into troubles.

For the line graph widget, they would like it to show the last 52 weeks worth of data points. I have the main log going reverse chronological, and adding new entries to the top, as I am not sure how to take 52 values from the bottom... I have a secondary log that puts all of the data in regular chronological, so it shows on the widget correctly, but when a new entry is added to the main log, the sec. one does not update at all, and stays referenced to the original data, instead of the specific row.

Maybe I am going about this wrong, but it seems impossible to both show the data on a chart with the newest week to the right, as well as only showing the last years worth of overtime. Does anyone have any ideas?

Thank you