Linux: Process file in reverse

This returns the number 200 just as it should, because there are 200 lines in the file:

#!/bin/bash
while read MONTH DAY TIME DATA
do
 COUNT=$((COUNT+1))
done < $1
echo $COUNT

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When I try to do this in reverse it returns 1.

#!/bin/bash
while read MONTH DAY TIME DATA
do
 COUNT=$((COUNT+1))
done <<< $(tac $1)
echo $COUNT

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I am using CentOS.