measurements: avoid division by zero
measurements: avoid division by zero

telenoobie/osmo-bts,geosphere/osmo-bts,osmocom/osmo-bts,shimaore/osmo-bts,geosphere/osmo-bts,osmocom/osmo-bts,geosphere/osmo-bts,tacooper/osmo-bts,shimaore/osmo-bts,geosphere/osmo-bts,shimaore/osmo-bts,osmocom/osmo-bts,telenoobie/osmo-bts,telenoobie/osmo-bts,shimaore/osmo-bts,tacooper/osmo-bts,telenoobie/osmo-bts