Set a minimum level in contour plots

Specific Domains Visualization
, , ,
5

I get this:
Plots_python_plot_specific_contour_levels_legend

with this code:

using Plots; pythonplot(dpi=100)

f(X, Y) = (100/(3*s*k^2))*(((1-(X/Y)^2)^3))*(Y^4)

mₕ, v, mₜ, Nₜ = 125, 246, 172.76, 3
k= pi*mₕ*v
s = 1 - (Nₜ/(3*k^2))mₜ^4
X, Y = range(0, 200, 1000), range(0, 500, 2000)
Z = @. f(X', Y)
zc = [5, 10, 30, 70, 100]
contour(X, Y, Z, levels=zc, lw=2, colorbar_ticks=(zc,string.(zc) .* "%"), clims=extrema(zc))