Assistant API issue with interpreting JSON.stringified data

I converted my function calling response from JSON to string and then pass it back to Assistant API with openai.beta.threads.runs.submitToolOutputs, yet ChatGPT can’t seem to tell which day has the highest revenue. I’ve tried both gpt-3.5-turbo and gpt-4. What can I do to make ChatGPT better interpret my data?

This is how my stringified data looks like.