{{Percent-done|done=N|total=N|digits=N}}

done
The number of items completed (defaults to 0)
total
The total number of items in the task (defaults to 100, so this can be omitted if the first parameter is a percentage rather than an absolute quantity)
digits
The maximum number of digits to be displayed after the decimal point (defaults to 1)

Examples:

{{Percent-done|done=13|total=33}} produces: 13 (39.4%) done

{{Percent-done|done=20|total=50|digits=3}} produces: 20 (40%) done (only significant digits are displayed)

{{Percent-done|done=10.6564|digits=2}} produces: 10.6564 (10.66%) done