title: cAdvisor prometheus integration returns container_cpu_load_average_10s as 0
body: <p>I have configured Prometheus to scrape metrics from cAdvisor. However, the metric "container_cpu_load_average_10s" only returns 0. I am able to see the CPU metrics under the cAdvisor web UI correctly but Prometheus receives only 0. It is working fine for other metrics like "container_cpu_system_seconds_total". Could someone point if I am missing something here?</p>
  
  <p>Prometheus version: 2.1.0 </p>
  
  <p>Prometheus config:</p>
  
  <p><code>scrape_configs:
  - job_name: cadvisor
    scrape_interval: 5s
    metrics_path: /metrics
    scheme: http
    static_configs:
    - targets:
      - 172.17.0.2:8080</code></p>
  
  <p>cAdvisor version: 0.29.0</p>