SOURCE

<div class="circle" style="--completion: 20%">
    <span>50</span>
</div>

:root {
  --completion: 0%;
}
.circle {
    position: relative;
    display: flex;
    width: 100px;
    height: 100px;
    background: #fff;
    border: 4px double #fff;
    border-radius: 50%;
    justify-content: center;
    align-items: center;
    overflow: hidden;
}
.circle:after {
    content: '';
    position: absolute;
    top: calc(100% - var(--completion));
    left: 50%;
    width: 200px;
    height: 200px;
    background-color: #a4eafd;
    border-radius: 80px;
    translate: -50% 0;
    animation: spin 5s linear infinite;
    -webkit-animation: spin 5s linear infinite;
}
.circle span {
    z-index: 1
}

@-moz-keyframes spin {
  0% {
    -moz-transform: rotate(0deg);
    -o-transform: rotate(0deg);
    -webkit-transform: rotate(0deg);
    transform: rotate(0deg);
  }

  100% {
    -moz-transform: rotate(359deg);
    -o-transform: rotate(359deg);
    -webkit-transform: rotate(359deg);
    transform: rotate(359deg);
  }
}
@-webkit-keyframes spin {
  0% {
    -moz-transform: rotate(0deg);
    -o-transform: rotate(0deg);
    -webkit-transform: rotate(0deg);
    transform: rotate(0deg);
  }

  100% {
    -moz-transform: rotate(359deg);
    -o-transform: rotate(359deg);
    -webkit-transform: rotate(359deg);
    transform: rotate(359deg);
  }
}
@-o-keyframes spin {
  0% {
    -moz-transform: rotate(0deg);
    -o-transform: rotate(0deg);
    -webkit-transform: rotate(0deg);
    transform: rotate(0deg);
  }

  100% {
    -moz-transform: rotate(359deg);
    -o-transform: rotate(359deg);
    -webkit-transform: rotate(359deg);
    transform: rotate(359deg);
  }
}
@-ms-keyframes spin {
  0% {
    -moz-transform: rotate(0deg);
    -o-transform: rotate(0deg);
    -webkit-transform: rotate(0deg);
    transform: rotate(0deg);
  }

  100% {
    -moz-transform: rotate(359deg);
    -o-transform: rotate(359deg);
    -webkit-transform: rotate(359deg);
    transform: rotate(359deg);
  }
}
@keyframes spin {
  0% {
    -moz-transform: rotate(0deg);
    -o-transform: rotate(0deg);
    -webkit-transform: rotate(0deg);
    transform: rotate(0deg);
  }

  100% {
    -moz-transform: rotate(359deg);
    -o-transform: rotate(359deg);
    -webkit-transform: rotate(359deg);
    transform: rotate(359deg);
  }
}