def summary_table(params, proteins):
    """
    Returns a string representing a simple summary table of
    protein classifcations.
    """
    out = ''
    counts = {}
    for seqid in proteins:
        category = proteins[seqid]['category']
        if category not in counts:
            counts[category] = 1
        else:
            counts[category] += 1
    out += '\n\n# Number of proteins in each class:\n'
    for c in counts:
        out += '# %-15s %i\n' % (c, counts[c])
    return out
