public Object getValueAt(int rowIndex, int columnIndex) {
        StockMarketYear marketYear = market.getYearOffset(rowIndex);
        switch(columnIndex){
            case 0: return marketYear.year();
            case 1: return marketYear.startingBalance();
            case 2: return marketYear.startingCostBasis();
            case 3: return marketYear.totalSold();
            case 4: return marketYear.growth();
            case 5: return marketYear.endingBalance();
            default: throw new UnreachableCodeException();
        }
    }