public List<List<Double>> readData() {
        List<List<Double>> data = new ArrayList<List<Double>>();

        HSSFSheet sheet = wb.getSheetAt(0);
        Iterator<Row> rowIt = sheet.iterator();
        if (rowIt.hasNext()) {
            rowIt.next();	//skip caption row
        }
        while (rowIt.hasNext()) {
            Row row = rowIt.next();

            List<Double> curRow = new ArrayList<Double>();
            for (Cell cell : row) {

                curRow.add(cell.getNumericCellValue());

            }
            data.add(curRow);
        }

        return data;
    }