Struggling with Data Step retain function

[bknitch]

Data set is below.

I would like to retain the Max YEAR with the corresponding FIRST_FOUND detail. I've tried a retain statement but it seems its not working. Not sure if I am able to create a MAX(YEAR) within in a data step or if i will have to create that in a proc sql prior to performing my data step. Any assistance would be appreciated. 

Primary_ID	Secondary_ID	YEAR	CONDITION	STATUS	FIRST_FOUND	count
1ABCDEFG2345	4567	2014	108	NEW	IT	0
1ABCDEFG2345	4567	2015	108	DROPPED		1
1ABCDEFG2345	4567	2016	108	DROPPED		2
1ABCDEFG2345	4567	2017	108	DROPPED		3
1ABCDEFG2345	4567	2018	108	DROPPED		4
1ABCDEFG2345	4567	2019	108	DROPPED		5

This is how i would like my data to look 

Primary_ID	Secondary_ID	DOS_YEAR	CONDITION	STATUS	FIRST_FOUND	count
1ABCDEFG2345	4567	2018	108	NEW	IT	5

Code Below:

data source_detail_1 (keep=Primary_ID Secondary_ID YEAR CONDITION STATUS FIRST_FOUND COUNT YEAR1 );
set source_detail (where=(PRIMARY_ID='1ABCDEFG2345')) ;
retain first_found;
YEAR1= MAX(YEAR);
run;

[bknitch · Accepted solution]

Solved myself 

proc sort data=WORK.SOURCE_DETAIL; by primary_id year descending first_found ;run;
data temp1;
set WORK.SOURCE_DETAIL;
length first_found1 $3.;
retain first_found1 ;
by primary_id year descending first_found ;
if first.primary_id then do;
first_found1=first_found;
end;
output;
drop first_found;

run;