$ curl -sS -o m#1 'http://tinymicros.com/pm/index.php?goto=MonkBirthdays&start={0,50,100,150,200,250,300,350,400,450,500,550,600,650}'
$ perl -le 'for (0..13) {$x=$_*50;$y=sprintf q{%02d}, $_; system(qq{mv m$x monk_birthday_$y.html})==0 or die;}'
$ perl -wlne 'print $1 if m{^<TD BGCOLOR="#CCCCFF" ALIGN="RIGHT"><NOBR>(\d{4}-\d{2}-\d{2})</NOBR></TD>$};' m* > dates.dat

$ vi dates.dat
 656 birthdays
-  4 are over 100
- 38 give birthday but not birthyear
-  5 are 7 years old or less
-  1 is negative (time traveler?)
 ---
 608 valid birthdays

$ perl -MDateTime -MDateTime::Format::ISO8601 -wlne 'BEGIN{$today=DateTime->today()} my $dt = DateTime::Format::ISO8601->parse_datetime($_) or die; print $today->subtract_datetime($dt)->years'        dates.dat > ages_in_years.dat
$ perl -MDateTime -MDateTime::Format::ISO8601 -wlne 'BEGIN{$today=DateTime->today()} my $dt = DateTime::Format::ISO8601->parse_datetime($_) or die; print $today->subtract_datetime($dt)->delta_months' dates.dat > ages_in_months.dat

$ perl -wlne '$h{int($_/10)}++; END{printf qq{%7d\t%d-%d\n}, $h{$_}, $_*10,($_+1)*10-1 for sort keys %h}' ages_in_years.dat
     10 10-19
    224 20-29
    279 30-39
     73 40-49
     18 50-59
      4 60-69

$ perl -wlne '$c++; $t+=$_; END{print "Average: ", $t/$c/12}' ages_in_months.dat
Average: 33.1097861842105