How can I skew certain y-axis values on a line chart in ECharts?

I’m building a line chart in ECharts, but I want to skew/weight a specific range of the y-axis to be larger than it would be linearly. For example, I would like values 0-70 to take up 1/3 of the chart size and the remaining 70-100 to take up 2/3. I don’t have much experience with charting, so I’m a little lost on the best approach.

Here are the ECharts options I’m using to create the line chart, also available in this Codesandbox:

import { format } from "date-fns";
import { createFakeValues } from "../utils";

const dataValues = createFakeValues({
  yValues: [29, 32, 35, 40, 47, 49, 50, 49, 48, 45, 43, 39, 35, 30, 27, 25, 24],
  startDate: new Date("2024-12-01T18:27:08.199Z"),
  dateDeltaMs: 1800000,
});

const eChartsDataValues = dataValues.map((dv) => [dv.date, dv.value]);

export const eChartsOptions = {
  dataset: [
    {
      source: eChartsDataValues,
      dimensions: ["timestamp", "value"],
    },
  ],
  xAxis: {
    type: "time",
  },
  yAxis: {
    min: 0,
    max: 50,
  },
  series: [
    {
      name: "Y Level",
      type: "line",
      smooth: true,
      datasetIndex: 0,
      showSymbol: false,
      encode: {
        x: "timestamp",
        y: "value",
      },
      markArea: {
        silent: true,
        emphasis: {
          disabled: true,
        },
        label: {
          fontSize: 12,
          textBorderColor: "transparent",
          position: "insideBottomLeft",
        },
        data: [
          [
            {
              name: "This is mathematically a shorter range (40-50), but it should take up the majority of space on the graph",
              yAxis: 40,
              itemStyle: {
                color: "red",
              },
            },
            {
              yAxis: 50,
            },
          ],
          [
            {
              name: "This is mathematically a bigger range (0-40) but should take up a smaller section of the graph",
              yAxis: 0,
              itemStyle: {
                color: "green",
              },
            },
            {
              yAxis: 40,
            },
          ],
        ],
      },
    },
  ],
};