I am using R and have found that both KPSS ( Kwiatkowski-Phillips-Schmidt-Shin ) and the adf (Dickey-Fuller) tests indicate stationarity, having a **p-value of 0.01**.

Here is a plot of the original data:

![enter image description here](https://i.stack.imgur.com/3kOYE.png)

However, when I plot the correlogram, it looks as though the data are non-stationary.

![enter image description here](https://i.stack.imgur.com/wWdrx.png)

So what do you think? Is the data stationary or non-stationary?