Functional Modules to get day of year based on Sy-datum

Hi Friends,

Requirement is to create Customer Exit which returns day of year.

Is there any date functional module which returns day number of year.

I need to get day of year based on SY-DATUM.

Say for

31st Jan 2016 should return 31

01st Feb 2016 should return 32

02nd Feb 2016 should return 33

.

.

.

31st Dec 2016 should return 365

Thanks in advance.

Regards,

Sunil