task
Essentially, count the number of occurrences of =={{header| on each task page.

Output:

100 doors: 20 examples.
99 Bottles of Beer: 29 examples.
Abstract type: 10 examples.

Total: X examples.
For a full output, updated periodically, see Rosetta Code/Count examples/Full list.

You'll need to use the Media Wiki API, which you can find out about locally, here, or in Media Wiki's API documentation at, API:Query

ConvertUTF8 := proc( str )
        local i, tempstring, uniindex;
       try
           tempstring := str;
           uniindex := [StringTools:-SearchAll("\u",str)];
           if uniindex <> [] then
               for i in uniindex  do
                   tempstring := StringTools:-Substitute(tempstring, str[i..i+5], UTF8:-unicode(str[i+2..i+5]));  
               end do:
           end if;
           return tempstring;
       catch:
           return str;
       end try;
   end proc:
print_examples := proc(lst)
	local task, count, url, headers, item;
	for task in lst do
		count := 0:
		url := cat("http://www.rosettacode.org/mw/index.php?title=", StringTools:-Encode(StringTools:-SubstituteAll(task["title"], " ", "_"), 'percent'), "&action=raw"):
		headers := [StringTools:-SearchAll("=={{header|",URL:-Get(url))]:
		for item in headers do
			count++:
		end do:
		printf("%s has %d examples\n",ConvertUTF8(task["title"]), count);
	end do:
end proc:
 
 
x := JSON:-ParseFile("http://rosettacode.org/mw/api.php?action=query&list=categorymembers&cmtitle=Category:Programming_Tasks&cmlimit=20&format=json"):
print_examples(x["query"]["categorymembers"]);
while(assigned(x["continue"]["cmcontinue"])) do
	continue := x["continue"]["cmcontinue"]:
	more_tasks:= cat("http://rosettacode.org/mw/api.php?action=query&list=categorymembers&cmtitle=Category:Programming_Tasks&cmlimit=20&format=json", "&continue=", x["continue"]["continue"], "&cmcontinue=", x["continue"]["cmcontinue"]):
	x := JSON:-ParseFile(more_tasks):
	print_examples(x["query"]["categorymembers"]);
end do:
 