public void addLocation(int jaar, int maand, DataPoint location)
	{
		boolean found =false;
		
		for (Period per: this.periods)
		{
			if (per.jaar == jaar && per.maand == maand)
			{
				found =true;
				per.addLocation(location);
			}
		}
		
		if (!found)
		{
			Period per = new Period(jaar,maand);
			per.addLocation(location);
			this.addPeriod(per);
		}
	}