show accurate year

app/controllers/categories_controller.rb

@@ -13,7 +13,8 @@ class CategoriesController < ApplicationController
   def show
     district = @school.district
     authenticate(district.name.downcase, "#{district.name.downcase}!")
-    @school_category = SchoolCategory.for(@school, @category).first
+    @year = (params[:year] || "2017").to_i
+    @school_category = SchoolCategory.for(@school, @category).in(@year).first
     @child_school_categories = SchoolCategory.for_parent_category(@school, @category).valid
     @questions = @category.questions
   end

app/views/layouts/_school_header.html.haml

@@ -3,7 +3,11 @@
     =# link_to(image_tag(@district.logo), @district) if @district.present?
     %h2= link_to @school.name, @school
     = simple_format(@school.description)
-    %p Data from 2016-2017 school year.
+    - if @year.present?
+      %p
+        Data from
+        = "#{@year - 1}-#{@year}"
+        school year.
     - if @school.district.present?
       %p
         %strong District: