loop through each line in a text file

[qtrimble]

I'm a python newbie but I do have some basic scripting experience.  I
need to take the line starting with "wer" and extract the year and day
of year from that string.  I want to be able to add the year and day
of year from the last line having "wer*" to the lines occurring in
between "wer*" lines.  Python seems suitable to do this and I'm fairly
certain I can eventually get this to work but I've been hit with a
very short time frame so I'm looking for any generous help.  The data
below is just a sample.  There are well over 500,000 lines that need
processed.

wer1999001
      31.2234      82.2367
      37.9535      82.3456
wer1999002
      31.2234      82.2367
      37.9535      82.3456