Read text file and Calculate daily flows by date

[tienxviet]

I'm trying to sort and calculate a huge text file.
I'd like calculate the daily flow by month/year first.
and then also for Annual along with the station code.
I think you'd have to skip the first 27 lines to begin reading the data.
I'd like for it to output something along the lines of..

For Ex:
Station Code Month Flow(cfs) : Annual Flow(cfs)
02429900 June 1973 ----- 1973 ------
02429900 July 1973 ----- 1972 ------
etc.

I've attached the text file.
But here's some of the file. (Disregard the A and Ae)

USGS 02429900 1973-06-01 21 A
USGS 02429900 1973-06-02 19 A
USGS 02429900 1973-06-03 17 A
USGS 02429900 1973-06-04 16 A
USGS 02429900 1973-06-05 15 A
USGS 02429900 1973-06-06 30 A
USGS 02429900 1973-06-07 26 A

Anything will be of help.
Thanks