text: select distinct make, 
  		model_year, 
  		sum(sum),
  		lead (model_year, 1, 'none') 
  			over (partition by make order by make, model_year) as lead_model_year_1,
  		lag (model_year, 2, 'blank') 
  			over (partition by make order by make, model_year) as lag_model_year_2
  from alternatebyfuel
  where make like 'A%'
  group by make, model_year
  order by make, model_year
  -- where make = 'TOYOTA'
  -- limit 80;