def percentGC(x):
    """ Calculate the percent GC content of a nucleotide string
    Return result rounded to two decimal places

    x = nucleotide string
    """
    y = list(x)
    l = len(y)
    Q = {'A': 0, 'C': 1, 'G': 1, 'T': 0}
    z = sum([Q[x] for x in y]) / l
    return round(z, 2)