def _percent_str(percentages):
    """Convert percentages values into string representations"""
    
    pstr = []
    for percent in percentages:
        if percent >= 0.1:
            pstr.append('%.1f' %round(percent, 1)+' %')
        elif percent >= 0.01:
            pstr.append('%.2f' %round(percent, 2)+' %')
        else:
            pstr.append('%.3f' %round(percent, 3)+' %')
    
    return pstr