Here, this plot shows the number of customers served per day from 1 jan 2018 to 31 dec 2019.
I grouped the entire data by each month and calculated the average and variance per month.
I also ran an augmented dickey-fuller test and got the following result
ADF Statistic: -26.031963 p-value: 0.000000
Since, the mean and variance do not vary too much, should I infer that the data is stationary?