Number formats

Axis and data-label number formats live on axis label config:

axes: {
  left: {
    labels: {
      format: {
        prefix: '',
        postfix: '',
        thousandSeparator: ',',
        decimalSeparator: '.',
        decimalPlaces: 0,
        forceDecimals: true,
        signDisplay: 'auto',
        scaleDown: 0,
      },
    },
  },
}

Percentage chart types (stackedBar100, area100, mekko) often use postfix: '%'.