{% for post in site.posts %}
{% assign post_year = post.date | date: "%Y" %}
{% if post_year != year %}
{% unless forloop.first %}
{% endunless %}
{{ post_year }}
{% assign year = post_year %}
{% endif %}
-
{{ post.title }}
{{ post.date | date: "%m/%d" }}
{% if forloop.last %}
{% endif %}
{% endfor %}