Not sure what the best way is to structure my DB

So I’m trying to take a snapshot of a game’s inventory (saved to a .json file) every 30 seconds or 60 seconds.
With the goal of having a graph that allows me to see which items in the inventory go up and down over time.
The game has about 200-300 items for now but it’ll probably expand a lot over time.
Basically i’m saving “amount of itemid ‘12’ = 50” and that times 200-300 about every 30-60 seconds. (it’ll only save data points when the game is actually being played.How do I structure my db to do this correctly and not cause performance problems?

The structure of the game files are that there can be multiple sets of inventories as well btw

EDIT: this is an example of a save file from the game: