$ perl -nE '$l++; $i += () = $_ =~ /\bfoo\b/g; say "After line $l: $i"' 1176022.txt 
After line 1: 1
After line 2: 2
After line 3: 2
After line 4: 4
After line 5: 4
After line 6: 5
After line 7: 5
$