Don't show zeros in cohorts

app/controllers/blazer/queries_controller.rb

@@ -104,7 +104,7 @@ def run
       @run_id = blazer_params[:run_id]
 
       run_cohort_analysis if @cohort_analysis
-
+      
       query_running = !@run_id.nil?
 
       if query_running

app/views/blazer/queries/_cohorts.html.erb

@@ -5,12 +5,13 @@
   </p>
 <% end %>
 <% if @rows.any? %>
+  <% cohort_period_cols = @rows.map(&:length).max - 2 %>
   <div class="results-container">
     <table class="table results-table">
       <thead>
         <tr>
           <th style="min-width: 100px;">Cohort</th>
-          <% 12.times do |i| %>
+          <% cohort_period_cols.times do |i| %>
             <th style="width: 7.5%; text-align: right;"><%= @conversion_period.titleize %> <%= i + 1 %></th>
           <% end %>
         </tr>
@@ -22,10 +23,10 @@
               <%= row[0] %>
               <div style="font-size: 12px; color: #999;"><%= row[1] == 1 ? "1 user" : "#{number_with_delimiter(row[1])} users" %></div>
             </td>
-            <% 12.times do |i| %>
+            <% cohort_period_cols.times do |i| %>
               <td style="text-align: right;">
                 <% num = row[i + 2] %>
-                <% if num %>
+                <% if num && !num.zero? %>
                   <% denom = row[1] %>
                   <% if denom > 0 %>
                     <%= (100.0 * num / denom).round %>%