The annual number of passengers on flight Global Air $01$ from Boston to Bermuda has been tabulated for four years.

$\backslash$table$[[$Season$,$Year,$],[2018,2019,2020,2021],[$Winter$,38,36,38,44],[$Spring$,25,28,18,20],[$Summer$,38,32,36,41],[$Fall$,33,40,44,43]]$

What is the seasonal index for Winter?

Round to two decimal digits.