def get_aa_percentage(sequence, aa_list=['A','I','L','M','F','W','Y','V']):
    """ Calculates percentage of sequence made up of amino acids in aa list.
    If no list is given, default is hydrophilic amino acids.  """
    #  Right format
    sequence = sequence.upper()
    aa_list = [aa.upper() for aa in aa_list]
    aa_count = 0
    #  Add counts of all amino acids
    for aa in aa_list:
        aa_count += sequence.count(aa)
    #  Obtain percentage and round
    return round(100*aa_count/len(sequence), 2)