def METHOD_NAME(self, t=-1, ax=None, show=None, **kwargs):
    """
    Create a histogram of the ion charge state densities.
    """
    genax = ax is None
    if genax:
        ax = plt.axes()
        if show is None:
            show = True
    x = [0]
    y = [0]
    labels = ['']
    for i in range(len(self.ions)):
        ion = self.ions[i]
        for state in ion.ionstates:
            x.append(x[-1]+1)
            y.append(state.integral(t=t))
            labels.append(state.getRomanName())
    x = x[1:]
    y = y[1:]
    labels = labels[1:]
    #ax.hist(y, weights=x)
    ax.bar(x, y, tick_label=labels, **kwargs)
    lbls = ax.get_xticklabels()
    plt.setp(lbls, rotation=45)
    if show:
        plt.show(block=False)
    return ax