Start with a really simple test.
Since this is your third year, I'm assuming Y2 was done manually. Use that dataset and point claude code to it. Include all the metrics you want it to report on and leave it really simple. Cross check the output with your report. If the data points are in line, the theory works. Then point it at the new data. You could even add Y2 report to the prompt so that it knows the format.
One more piece of advice. Request the output as an HTML. It's so much easier for you to read, it can handle diagrams and charts and doesn't take too much more resources than a .md file.
