Count how many times a strings appear in random generator

I have a while loop with an string array and a simple randomize for them.

My problem however is to count how many times the same strings have appear when the loop was running.

Ex :
oc/open string has appeared 3 times
rw/read string has appeared 2 times
oc/close string has appeared 3 times

etc....

At the moment im using if else methods inside the loop, but there must be a better way to count them? Any tips?

function injection { 
COUNTER=0
countopen=0
while [ $COUNTER -lt 10 ]; do

module[0]="oc/open"
module[1]="oc/close"
module[2]="rw/read"
module[3]="rw/write"

randModule=$[$RANDOM % ${#module[@]}]
export MODULE=${module[$randModule]}
echo $MODULE

    if [ $randModule == 0 ]; then
        let countopen++
#let countclose++
#etc
#etc

    fi
let COUNTER++
done
    echo "Open $countopen"
}

injection