check_redis.pl get hit rate with previous perf data

[rndmania]

$USER1$/check_redis.pl -H $HOSTADDRESS$ -R -f -P "$SERVICEPERFDATA$"

but return value is total hit rate

so, I test manually
./check_redis.pl -H host_addr -R -f -P "keyspace_hits=89737856c keyspace_misses=35252550c"

but also return value is total hit rate

how get real hit rate?

thank you