请教大家个问题，如何对不同长度的观测值计数，并且，用proc freq看它的分布 [推广有奖]

data a;
input PSC $1-6 province$ ;
datalines;
M2J1z3  ONH1Y1C6  QCM221z1  ON M2J1z2  ON M2J z3   ON M1z3     ON H2Y1C6  QC2Y1C6   QCH6 1C6  QCH243C3  QC

run;

data postcode;
set a;
postcode=compress(psc);
run;
之后，对于去掉空格的ｏｂｓ，进行计数，得出含４，５，６位ｐｏｓｔｃｏｄｅ的分布比例？
proc freq data = postcode2;
tables postcode;
run;

谢谢各位高手了