The way I implemented this was by creating a text span that would hold the dynamic date and giving it the ID “year”. I then targeted that ID by placing this code in the footer custom code section:
<script type="text/javascript">
// Get the current year and put it in a variable
var year = new Date().getFullYear().toString();
// Write the date into element with ID "year"
document.getElementById("year").innerHTML = year;
</script>