$ echo '
> 1   11/12/2014 9:46 A
> 2   11/12/2014 9:47 B
> 3   11/12/2014 9:48 A
> 4   11/12/2014 9:49 A
> 5   11/12/2014 9:50 A
> 6   11/12/2014 9:51 A
> 7   11/12/2014 9:52 B
> 8   11/12/2014 9:53 B
> 9   11/12/2014 9:54 B
> 10  11/12/2014 9:55 B
> 11  11/12/2014 9:56 B
> 12  11/12/2014 9:57 C
> 13  11/12/2014 9:58 C
> 14  11/12/2014 9:59 C
> 15  11/12/2014 10:00    A
> 16  11/12/2014 10:01    B
> 17  11/12/2014 10:02    C
> 18  11/12/2014 10:03    C
> '  |  perl -nE 'chomp; $h{$1}++ if /(\w\s*$)/; END { say "Letter $_ appears $h{$_} times"  for keys %h;}'
Letter A appears 6 times
Letter C appears 5 times
Letter B appears 7 times