def width_bar(perc):
    """This function returns the width of the bar graph. 
       Parameters
       ----------
       perc : float coverage value, e.g. 82.71
       
       Returns
       ----------
       width : float width of graph, eg: 4.5
    """
    # Return a proportionate value of the input percentage
    width = perc / 20
    # Default width to 1.5
    if width < 1:
        width = 1.5
    return width