Как добавить несколько строк заголовка, используя таблицу угловых материалов

Question

Параметр 1: период времени {{}} Element.value Параметр 2: Пол {{}} Element.gender

<ng-container matColumnDef="column3">
  <mat-header-cell *matHeaderCellDef rowspan="2"> Patients with Base Condition </mat-header-cell>
  <mat-cell *matCellDef="let element"> {{element.value}} </mat-cell>
</ng-container>

<ng-container matColumnDef="column4">
  <mat-header-cell *matHeaderCellDef> Patients with Outcome</mat-header-cell>
  <mat-cell *matCellDef="let element"> {{element.value}} </mat-cell>
</ng-container>

<ng-container matColumnDef="column5">
  <mat-header-cell *matHeaderCellDef class="ColumnDivider"> Prevelance </mat-header-cell>
  <mat-cell *matCellDef="let element" class="ColumnDivider"> {{element.value}} </mat-cell>
</ng-container>

<ng-container matColumnDef="column6">
  <mat-header-cell *matHeaderCellDef> Patients at Risk </mat-header-cell>
  <mat-cell *matCellDef="let element"> {{element.value}} </mat-cell>
</ng-container>

<ng-container matColumnDef="column7">
  <mat-header-cell *matHeaderCellDef> New Patients with Outcome </mat-header-cell>
  <mat-cell *matCellDef="let element"> {{element.value}} </mat-cell>
</ng-container>

<ng-container matColumnDef="column8">
  <mat-header-cell *matHeaderCellDef class="ColumnDivider"> Incidence Proportion </mat-header-cell>
  <mat-cell *matCellDef="let element" class="ColumnDivider"> {{element.value}} </mat-cell>
</ng-container>

<ng-container matColumnDef="column8">
  <mat-header-cell *matHeaderCellDef> Total Patient Years at Risk </mat-header-cell>
  <mat-cell *matCellDef="let element"> {{element.value}} </mat-cell>
</ng-container>

<ng-container matColumnDef="column10">
  <mat-header-cell *matHeaderCellDef class="myMarginLeft"> New Patients with Outcome </mat-header-cell>
  <mat-cell *matCellDef="let element" class="myMarginLeft"> {{element.value}} </mat-cell>
</ng-container>

<ng-container matColumnDef="column11">
  <mat-header-cell *matHeaderCellDef >Incidence Rate </mat-header-cell>
  <mat-cell *matCellDef="let element"> {{element.value}} </mat-cell>
</ng-container>

<ng-container *matHeaderRowDef="displayedColumns">
  <div class="mat-header-row header-group-row">
    <div class="mat-header-cell" role="columnheader"></div>
    <div class="mat-header-cell" role="columnheader"></div>
  </div>
  <mat-header-row></mat-header-row>
</ng-container>
<mat-row *matRowDef="let row; columns: displayedColumns;" (click)="getRecord(row)" [ngClass]="{'highlight': selectedRowIndex == row.inp_analysis_name}"></mat-row>

Несколько столбцов с одним столбцом.

column1 | column2 | Column3 | column4 | Column5 | Column6 | Column7 | Column8 Столбец2.1 | Столбец2.2 | Столбец2.3 Столбец6.1 | Столбец6.2