Find a sensible way of interpolating the data you just plotted.
Add the curve thus obtained to the plot in the previous question. You may notice
that there is some roughness in your plot that indicates that we are at the limit of
what we can sensibly analyse.
Note: this question is stated purposefully vaguely to give you a chance to
showcase your talent (or your prowess with Google). As a timely reminder, any use
of code found online must be carefully referenced, otherwise it will be deemed
plagiarism

You are now in a position to clearly separate overall trend,
seasonal variation, and residual effects. Finish the project by creating a plot of the
residual noise, similar to the bottom graph in the image below. Describe how the
residual effects compare to the seasonal variation.
(You are welcome to provide all four plots together, but you will only be assessed
on plotting the residual effects.)