Exercise 6.9.5. Shumway (1988) reports data from Waldmeier (1960-1978, 1961) on the number of sunspots from 1748 to 1978. The data are collected monthly, and a symmetric moving average of length 12 has been applied. The data in Table 6.7 are the moving averages corresponding to June and December (read across rows).

Do a frequency analysis of these data including appropriate confidence intervals and plots.