Huge table level Fragmentation caused in one table

Hi All,

we have an oracle 11.1.0.7.0 database.

In one of the tables, there is only INSERT happening on weekdays (load) and weekend purge (DELETE). But the fragmentation due to the DML is very huge compared to other tables in the same DB.

Below are the table creation parameters for the table:

PCTUSED    0
PCTFREE    10
INITRANS   11
MAXTRANS   255
STORAGE    (
            INITIAL          152M
            NEXT             1M
            MINEXTENTS       1
            MAXEXTENTS       UNLIMITED
            PCTINCREASE      0
            BUFFER_POOL      DEFAULT
           )

    
We had done a defragmentation before 4 months. The table has grown upto 75GB compared to actual size of 3.5 GB.

Note: The table has only NUMBER, VARCHAR, TIMESTAMP columns. Any information will be really helpful.