Change color of number depending on number value

I have data json content on numbers in percentage , those numbers are start 0.0 . I want to change color of those number if highs , lowers or in middle .

my pipe

@Pipe({
  name: 'precntColors'
})
export class PrecntColorsPipe implements PipeTransform {

  transform(value: any, args?: any): any {

    let d = value
    if (value >Math.round(0) && value<=Math.round(15)) {
      d="green"
    }
     else if (value>Math.round(16) && value<=Math.round(49)) {
      d="yellow"
    }
     else if (value>Math.round(50) && value <=Math.round(100)) {
      d="red"
    }
    return d; 

  }

}

html

<div [ngClass]='myda.percentage.canceled |precntColors'>

                </div>

When i run my app l got all number in green color ! and others colors are not showing . any ideas please ?