{
let ribbon = vl.markArea({opacity: 0.2})
.encode(
vl.y().fieldQ("low").scale({zero: false}),
vl.y2().fieldQ("high")
)
let line = vl.markLine()
.encode(vl.y().fieldQ("avg_correct").title("Test Score"))
return vl.layer(ribbon, line)
.encode(
vl.x().fieldQ("Eng_start").title("Age when started learning English").axis({tickCount: 4}),
vl.color().fieldN("age_group").scale({scheme: "set2"}).title("Current Age").legend({orient: "bottom", symbolOpacity: 1})
)
.data(data_)
.render()
}