'counts for each coordinate the number of feasible values in
``solutions`` and returns an array of length ``len(solutions[0])``
with the ratios.
`solutions` is a list or array of repaired `Solution` instances'

def feasible_ratio(self, solutions):

    count = np.zeros(len(solutions[0]))
    for x in solutions:
        count += (x.unrepaired == x)
    return (count / float(len(solutions)))
