Interval for ICMP check. Failover

Hi!
Question about the load-balancing. I have:

set load-balancing wan interface-health eth1 failure-count '2' set load-balancing wan interface-health eth1 nexthop 'gw-1' set load-balancing wan interface-health eth1 success-count '1' set load-balancing wan interface-health eth1 test 10 resp-time '3' set load-balancing wan interface-health eth1 test 10 target '8.8.4.4' set load-balancing wan interface-health eth1 test 10 type 'ping' set load-balancing wan interface-health eth1 test 20 resp-time '3' set load-balancing wan interface-health eth1 test 20 target '8.8.8.8' set load-balancing wan interface-health eth1 test 20 type 'ping' set load-balancing wan interface-health eth2 failure-count '2' set load-balancing wan interface-health eth2 nexthop 'gw-2' set load-balancing wan interface-health eth2 success-count '1' set load-balancing wan interface-health eth2 test 10 resp-time '3' set load-balancing wan interface-health eth2 test 10 target '8.8.4.4' set load-balancing wan interface-health eth2 test 10 type 'ping' set load-balancing wan interface-health eth2 test 20 resp-time '3' set load-balancing wan interface-health eth2 test 20 target '8.8.8.8' set load-balancing wan interface-health eth2 test 20 type 'ping' set load-balancing wan rule 10 description 'main load-balancing' set load-balancing wan rule 10 inbound-interface 'eth0' set load-balancing wan rule 10 interface eth1 weight '1' set load-balancing wan rule 10 interface eth2 weight '1' set load-balancing wan rule 10 protocol 'all'

What is the interval for the ICMP check? How many times per second/minute is the ICMP request? I did not find any settings regarding this.
Thanks