Hi,
You can maintain constant as 2.16 in the base entitlement of leave quota and select the radio button accrual period.
In the generation rule select the monthly radio button under the accrual period tab.
So when you will generate the quota through RPTQTA00 then system will generate the quota monthly and in the Validity & Deduction period of the quota.In the deduction give 1year after the Validity start.
Check and let me know.
Regards,Sankarsan