I'm new in the time series, so I need some help. I have a short time series (5 quarters), with the proportion of a parameter (public transport-user people). I know there are some effects of TS (trend, seasonal, cyclic and random).

I would like to testing the (significant) difference of two quarters's proportions, such as is there any difference between the proportion of public tranport users of the 4th quarter and the 5th one.

My first question is that sould I firstly test, that my time series is stational in this case.

My second question is that, if it is stational, could I use 'general' significant test?

My third one, if it's not stational, how can I test the differences?

Thanks in advance!