              20                                4000～6500                                  77%                   1.  20                                                        5        1972                  200   350                  5               1976                             FD1.5～100                                           2.                             1978                                        97              1980                                                                                                             139    233           3.                            1983                                       1984             9                14       1989      58                              95%                                                                                                                                          1  12～20                       1989                5  100                                