percent_filter.py

from decimal import Decimal, ROUND_DOWN

def percent_filter(value):
    """
    Format percentage
    """
    if value == 0:
        return '0%'
    elif value == 100:
        return '100%'
    elif value > 0 and value < 1:
        return '<1%'
    else:
        return '{:.1f}%'.format(Decimal(value).quantize(Decimal('.1'), rounding=ROUND_DOWN))