I have a plot of 10 incidence rates across time (see picture). I want to calculate the 95% confidence interval for each rate. It would be easiest to just do a normal distribution calculation, but I'm concerned this is not applicable here. For one, they are rare events. I thought to do a poisson distribution calculation for the confidence intervals  that is what is shown with the error bars in the attached picture. This was criticized with the comment  "Poisson assumes a constant rate over time". Assuming that is correct, what distribution/formula should I use to calculate my confidence intervals?
Thank you!
Thank you!
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