<svg width="300" height="100" viewBox="0 0 300 100"
  xmlns:xlink="http://www.w3.org/1999/xlink">
<defs>
  <mask id="fullmask" x="0" y="0" width="1" height="1"
      maskContentUnits="objectBoundingBox">
      <rect x="0" y="0" width="1" height="1"
          style="fill-opacity: 1.0; fill: white;"/>
  </mask>

  <mask id="opacityMask" x="0" y="0" width="1" height="1"
      maskContentUnits="objectBoundingBox">
      <rect x="0" y="0" width="1" height="1"
          style="fill-opacity: ; fill: white;"/>
  </mask>
</defs>

<g style="font-size: 14pt; text-anchor:middle; fill:black;">
  <g style="mask: url(#fullmask);">
    <circle cx="35" cy="35" r="25"/>
    <text x="35" y="80">100%</text>
  </g>

  <g style="mask: url(#opacityMask);">
    <circle cx="95" cy="35" r="25"/>
    <text x="95" y="80">75%</text>
  </g>
</g>

</svg>