# How do I identify if my time series' seasonality is additive or multiplicative?

The "ExponentialSmoothing" function in Python's "statsmodels.tsa.holtwinters" library gives you the option to set trend equal to additive or multiplicative but it also lets you set a seasonal parameter equal to additive or multiplicative. I believe the trend is additive when the peaks & troughs of the time series remain roughly the same. Is this correct? How do I determine if the seasonal parameter is additive or multiplicative?

Here is my time series plotted along with its decomposed plots: