Find out all reading per hour in Bookmates mongo activity database using map-reduce. Old mongo, no aggregates :(

readings.js

conn = new Mongo();
db = conn.getDB("publisher_bookmate");
db.getMongo().setSlaveOk();
var mapFunction1 = function() {
  emit(this.read_at, this.size);
};
var reduceFunction1 = function(keyCustId, readcount) {
	return Array.sum(readcount);
};
res=	db.getCollection("stats.reading_hourlies").mapReduce(
		mapFunction1,
		reduceFunction1,
		{
			out: { inline: 1 },
			query: {
				"read_at": { $gte: ISODate("2013-02-11T00:00:00Z")}
			}
		}
		)
//printjson(res)
var walk = function(o){
  for(var prop in o){
    if(o.hasOwnProperty(prop)){
      var val = o[prop];
      if (prop=="_id" || prop=="value") { print(val); }
      if(typeof val == 'object'){
        walk(val);
	}
    }
  }
};

walk(res.results)