Hello!

Using bash-Linux

I have a catalogue (with a header) of dates. What I want is, when the year change (from 2015 to 2016), I want to print a divide line ( ''*********************************************************************'') between them

An example of my current catalogue''

yyyy

2015 01 01

2015 01 02

2015 05 10

2016 01 02

2016 01 03

and what I want is

yyyy

2015 01 01

2015 01 02

2015 05 10

*********************

2016 01 02

2016 01 03

How do I do that?

Thank you in advance