public int getRowCount() {
            boolean isSummary = getUnitData().isSummary();

            int rows = 0;
            if (workingProfessionals.getColonists() > 0) rows++;
            if (workingAmateurs > 0) rows++;
            if (!isSummary && otherWorkingAmateurs.getColonists() > 0) rows++;
            if (teachers > 0) rows++;
            if (students > 0) rows++;
            if (!isSummary && otherStudents > 0) rows++;
            if (notWorking > 0) rows++;

            return rows;
        }