data trains;
do year = 2003 to 1975 by -1;
	time = year-1975;
	input trainkm t_coll tr_coll;	
    lgtrainkm = log(trainkm);
	output;
end;
cards;
518 0 3
516 1 3
508 0 4 
503 1 3 
505 1 2 
487 0 4 
463 1 1 
437 2 2 
423 1 2 
415 2 4 
425 0 4 
430 1 4 
439 2 6 
431 1 2 
436 4 4 
443 2 4 
397 1 6 
414 2 13 
418 0 5 
389 5 3 
401 2 7 
372 2 3 
417 2 2 
430 2 2 
426 3 3 
430 2 4 
425 1 8 
426 2 12 
436 5 2
;

proc genmod data=trains;
model tr_coll/trainkm = time / dist=poi link=log; run; 

proc genmod data=trains;
model tr_coll = time / dist=poi link=log offset=lgtrainkm; run;