protected override int Value(PointGroup <Sale> pointData) => pointData.Data().Any() ? Convert.ToInt32(pointData.Data().Sum(item => item.TotalValue()) / pointData.Data().Sum(item => item.Quantity())) : 0;
protected override int Value(PointGroup <Sale> pointData) => Convert.ToInt32(pointData.Data().Sum(item => item.TotalValue()));