Capacity Planning - Calculating db growth % of a specific db !

select
bf.file_size/1048576 as "File Size in MB",
bf.backup_set_id,
bf.file_type,
(case bf.file_type
when 'D' then 'Database'
when 'I' then 'Differential'
when 'L' then 'Log'
when 'F' then 'File/Filegroup'
when 'G' then 'File Differential'
when 'P' then 'Partial'
else
'Partial Differential'
end) as 'Type_Desc',
bf.logical_name,
bf.physical_drive,
bf.state_desc,

bs.user_name as "backed up by user",
bs.backup_start_date,
bs.backup_finish_date,
(convert(varchar,datediff(hh,bs.backup_start_date,bs.backup_finish_date))+':'+convert(varchar,datediff(mi,bs.backup_start_date,bs.backup_finish_date))+':'+convert(varchar,datediff(ss,bs.backup_start_date,bs.backup_finish_date))) as "Backup Window Time",
bs.compatibility_level,
bs.database_version,
bs.database_name,
bs.server_name,
bs.machine_name,
bs.collation_name,
bs.is_password_protected,
bs.recovery_model

into kabul

from
msdb.dbo.backupfile bf
join
msdb.dbo.backupset bs
on bf.backup_set_id=bs.backup_set_id

where bf.file_type='D'
and
bs.database_name='dumbo'
order by bf.backup_set_id

--with this a new table kabul is populated with statistical data
--The following tweaked query from table kabul will display the growth %
select
a.database_name,
(convert(numeric(5,2),(
(a.[file size in mb]/(select b.[file size in mb] from kabul b where b.backup_set_id=
(select max(x.backup_set_id)
from kabul x
join kabul y
on x.backup_set_id=y.backup_set_id
where x.backup_set_id<
a.backup_set_id))*100)-100))) "Growth %",
a.[Backup Window Time],
a.backup_set_id,
a.backup_start_date,
a.backup_finish_date,
a.[File Size in MB],
a.file_type,
a.Type_Desc,
a.logical_name,
a.physical_drive,
a.state_desc,
a.[backed up by user],
a.compatibility_level,
a.database_version,
a.server_name,
a.machine_name,
a.collation_name,
a.is_password_protected,
a.recovery_model
from
kabul a