totalAccumulator: function(acc, cell, row, row_count) {
    if (row.posting_date) {
        frappe.utils.report_total_accumulator(acc, cell, row, row_count);
    }
    if (cell.column.fieldname == "age" && cell.rowIndex === row_count-1) {
        const me = this;
        const n = me.bodyRenderer.visibleRows.filter(d => me.datamanager.getData(d.meta.rowIndex).posting_date).length;
        acc.content = flt(acc.content) / n;
    }
}