app/views/need_performance/_performance.html.erb
<h3 class="graph-title">Total pageviews for content responding to this need</h3>
<%= form_tag need_performance_path(need), method: :get, class: 'graph-settings' do %>
<ul>
<li>
<%= select_tag :period,
options_for_select(presenter.available_time_periods, presenter.current_time_period) %>
</li>
<li>
<%= select_tag :group,
options_for_select(presenter.available_time_groups, presenter.current_time_group) %>
</li>
</ul>
<%= button_tag 'Update graph', type: :submit, name: nil %>
<% end %>
<div class="graph">
<%= column_chart presenter.stacked_performance,
stacked: true %>
</div>