???? ????? ????????: ???? ???? ??????? ????? ?????? ????? ???? ???? ??? ?? ??????? ???????????? ?????? ?????? ?????????? ???? ????? ??? ???? ????? ?????? ?? ?????? ????? ?????? ?? ????? ?????? ????????. ???? ????? ?? ??????: ???? ?????? ???? ??? ?? ????? ??? ???????? beneath is a whole history of the quantity of groups performed in each period th