bash: multi stage pipelines with bash commands set in parentheses

x.sh

for i in {1..10}
do 
        bash -c '
                TIMEFORMAT=%3R
                time ( 
                        printf "%d\n" {1..10000} \
                        | while read; do echo $REPLY done > /dev/null;
                )
        '
done \
|& mawk '{ sum += $1 }; END { print sum / NR }'