proc summary data=my_data;
CLASS 类别;
VAR 人数;
output out= data_want sum=;
run;

年份 just change CLASS to 年份;

proc summary data=my_data nway;
CLASS 类别 年份;
VAR 人数;
output out= data_want sum=;
run;

if you want to use BY instead of CLASS, table need to be sorted first.

proc freq data = data;
tables 类别;
tables 年份;
tables 类别*年份;
run;