Question about plotting panel data?

[Raymond]

julia> using DataFrames

julia> using DataFramesMeta

julia> using RDatasets

julia> df = dataset("plm", "Grunfeld");

julia> gd = groupby(df, :Firm);

julia> p = plot(layout = 10)

julia> for i in 1:gd.ngroups
           data = @where(df, :Firm .== i)
           @df data plot!(p[i], :Year, :Inv)
       end

julia> display(p)

This is maybe not the best way to plot this graph.