How to find out db_growth_per_month for the last year

Run the following from sqlplus

set pagesize 50000
tti "Database growth per month for last year"

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')
/

tti off