Tree like structure in views I have a content type in which I have following fields 

Title, year, and report type. I create a block using BEF for exposed report type. which is working fine

Now I want to show results as 

- 2014 
    --Title1
    -- Title2
+ 2013 
     --Title 2013 
     --- Title 2013 1 


and so on 

When i click on + icon result will expand. 

Can we do this using views or I have to right custom code for this?
Maybe you should look at the Views tree module, to see how well it would fit your needs. Here is a quote about the module (from its project page):

... provides a tree-based style plugin for Views.
It is based off of the list style. Although it generates a nested view, there is still only a single query run for the view making it quite performant.