oracle database - sql for counting the columns with the same id with the one in current row

I have an oracle database and a few tables and with this query:

select rap.DENUMIRE,a3.ID,op.FK_ID,
    (SELECT COUNT(*) FROM ANEXA3_TABEL1_ROWS) AS count
from ANEXA3_TABEL1_ROWS a3
inner join RAPORTORI_AMB rap on rap.id = ch.FK_ID_RAPORTOR
inner join ANEXA3_TABEL1_OP op on op.FK_ID = a3.ID

the result is:

DENUMIRE    ID  FK_ID   COUNT
SC AAA      720 720     7
SC AAA      720 720     7
SC AAA      720 720     7
SC AAA      741 741     7
SC AAA      720 720     7
SC AAA      720 720     7
SC AAA      742 742     7

and I'd want to select in COUNT the number of columns with FK_ID equals to the ID in the current row. In this example, I'd want the following result:

DENUMIRE    ID  FK_ID   COUNT
SC AAA      720 720     5
SC AAA      720 720     5
SC AAA      720 720     5
SC AAA      741 741     1
SC AAA      720 720     5
SC AAA      720 720     5
SC AAA      742 742     1

Thanks in advance!