ctFormat.setDefaultRowHeight(15.0);
CTSheetView ctView = worksheet.addNewSheetViews().addNewSheetView();
ctView.setWorkbookViewId(0);
worksheet.addNewDimension().setRef("A1");
worksheet.addNewSheetData();
CTPageMargins ctMargins = worksheet.addNewPageMargins();
ctMargins.setBottom(0.75);