What smoothing variable would we need for this forecasting model?

Table 1 Sales for Kingsley Department Store, Sept '16 through Aug '20 January February March April May June July August September October November December 2.55 2.28 2.69 2.48 2.73 2.37 2.31 2.23 1.71 1.90 2.74 4.20 1.45 1.80 2.03 1.99 2.32 2.20 2.13 2.43 1.90 2.13 2.56 4.16 2.31 1.89 2.02 2.23 2.39 2.14 2.27 2.21 1.89 2.29 2.83 2.31 1.99 2.42 2.45 2.57 2.42 2.40 2.50 2.09 2.97 4.35