One option is to create one additional column to your table which indicates the maximum value possible and then create a line chart using that with fill below enabled.
Column 7 has just value 70 in all rows
Graph Builder(
Size(570, 798),
Variables(
X(:weight),
Y(:height),
Y(:Column 7, Position(1)),
Group X(:age),
Overlay(:than),
Color(:sex)
),
Elements(
Bar(X, Y(1), Legend(5), Response Axis("X")),
Line(Y(2), Color(0), Legend(8), Fill("Fill Below"))
),
SendToReport(
Dispatch({"Bar"}, "", OutlineBox, {Close(0)}),
Dispatch({"Line"}, "", OutlineBox, {Close(0)}),
Dispatch(
{},
"height",
ScaleBox,
{Min(0), Max(70.3382899628253), Inc(10), Minor Ticks(0)}
),
Dispatch(
{},
"400",
ScaleBox,
{Legend Model(
8,
Properties(0, {Line Color(35)}, Item ID("0", 1)),
Properties(-1, {Line Color(35)}, Item ID("Mean(Column 7)", 1))
)}
)
)
)
-Jarmo