If you use the BY
statement with the SAS system option NOBYLINE, which suppresses the
BY line that normally appears in output that is produced with BY-group
processing, then PROC MEANS always starts a new page for each BY group.
This behavior ensures that if you create customized BY lines by putting
BY-group information in the title and suppressing the default BY lines
with NOBYLINE, then the information in the titles matches the report
on the pages.
See Creating Titles That Contain BY-Group Information .
Also
see Suppressing the Default BY Line.