Dummy Monitor in Heartbeat.yml

Is it possible to create a monitor in heartbeat.yml that always sends 100% availability?

Would it look like this?

type: script
enabled: true
id: AlwaysAvailable
name: xxxx
script: |
echo "availability=100"
schedule: '@every 5m'
timeout: 15s
tags: ["xxxx", "Always Available"]

Furthermore how can I create a formula in Kibana Visualization that calculates the average of the daily availability values of all servers?