How to check Monthly Growth of database (tablespace)

As an DATABASE ADMINISTRATOR we always keep our eyes on FILE SYSTEM FREE SPACE. because we never want database got down because of SPACE ON SERVER.

with the below Statement we can monitor monthly database growth to forecast file system space

SQL Statement:
[code]
select to_char(creation_time, 'RRRR Month') "Month",
sum(bytes)/1024/1024 "Growth in Meg"
from sys.v_$datafile
where creation_time > SYSDATE-365
group by to_char(creation_time, 'RRRR Month');
[/code]
NOTE: USER REQUIRE ACCESS ON SYS.V_$DATAFILE to run the above statement / And this statement only show database (tablespace) growth.