How to append values to the list in shell script..?

#!/bin/bash
cd /pg
file=`ls -l |awk '{print $9}'`
list=()
for i in $a
do
   echo $i
   a=`cat /pg/$i | head  -n  1 |awk '{print $8}' ` #output: first interation 15 & 2nd values 60
   list+=($a)
   
   #a1=`cat /pg/$i | head -n 2 |awk '{print $8}'`
done
echo $list

through this a=`ls -l |awk '{print $9}'` I'm getting two file and iterating through for loop and appending values to list() the list should contains "15","16" but list contains only one value is "15" Please help me to fix the same.

# create list
hosts1=()
hosts2=()
# add hosts
hosts1+=( host1 )
hosts1+=( host2 )
hosts2+=( host3 )
hosts2+=( host4 )
# combine 2 lists
hosts1+=( ${hosts2[@]} )
# add some more
echo ${hosts1[@]}
hosts1+=( host5 )
hosts1+=( host6 )
echo ${hosts1[@]}