NOOBS suppresses the printing of observation numbers at the beginning
of the rows. N= prints the number of observations in a BY group at the end
of that BY group and (because of the SUM statement) prints the number of observations
in the data set at the end of the report. The first piece of explanatory text
that N= provides precedes the number for each BY group. The second piece of
explanatory text that N= provides precedes the number for the entire data
set.

proc print data=exprev noobs
n='Number of observations for the state: '
'Number of observations for the data set: ';