Need help in writing a arcade expression in Dashboard

[NikhileshUnnikrishnan]

I have a dataset with dates (start of the week), diseases, and their respective sample positivity (per_cent_positive) as follows:

This dataset gets updated every week, I want to use this data as an indicator in the ArcGIS dashboard. Still, I need this in the format below where city_pos_t is the latest sample positivity and city_pos_t-1 is the week before the latest.

It would be very helpful if anyone helps me with the arcade expression that can be used to get the above format. Thanks!