public int getItemCount() {
        return this.values.getRowCount();
    }

    /**
     * Returns the number of items in the specified series.
     * Returns the same as {@link CategoryTableXYDataset#getItemCount()}.
     *
     * @param series  the series index (zero-based).
     *
     * @return The item count.
     */
    public int getItemCount(int series) {
        return getItemCount();  // all series have the same number of items in