My x-axis data is currently in date (week) format, so my current code as part of a twoway graph is as follows to format the date to months and have 7 ticks:
, tlabel(#7, format(%twm))

The data is over two years, so I would like to please have a second line for my x-axis with 2020 below the first 4 dates, and 2021 below the 3 last dates.
This seems to be possible when working with categorical variables on the x-axis
e.g. xlabel(1 `" "PGM activity" "in previous conflict" "' 2 `" "no PGM activity" "in previous conflict" "', labsize(small))

But I cannot figure out an equivalent for date data.

Any help would be greatly appreciated!