The activemq-plugin-7.5.0.redhat-621070.jar management plug-in appears to have a bug in it that is causing the "Store Percent Usage" measurement to be 100 times larger then what it really is.
Similar issue has been reported for the "Memory Percent Usage" metric (see https://issues.jboss.org/browse/FUSEJON-97) and this seems to be fixed already.
I didn't check "Temp Percent Usage" measurement - but it is most likely that we need to fix the value plugin returns for this metric too.
This bug is referenced in knowledge solution: https://access.redhat.com/solutions/2438681. There is no workaround at this time.