Produce a stacked plot to present composited, site-level insect outbreak chronologies

plot_outbreak(x, disp_index = "mean_ngsi")

Arguments

x	an 'outbreak' object produced by `outbreak()`
disp_index	Identify the timeseries index to plot. Defaults to `mean_ngsi`, the average normalized growth suppression index for the site. The only other option is `mean_gsi`, the average growth suppression index.