What is the average weight and year for each year?
SELECT avg(Weight) ,  YEAR FROM CARS_DATA GROUP BY YEAR;
SELECT avg(Weight) ,  YEAR FROM CARS_DATA GROUP BY YEAR;
[{'avg(Weight)': 3441.3142857142857, 'Year': 1970}, {'avg(Weight)': 2960.344827586207, 'Year': 1971}, {'avg(Weight)': 3237.714285714286, 'Year': 1972}, {'avg(Weight)': 3419.025, 'Year': 1973}, {'avg(Weight)': 2877.925925925926, 'Year': 1974}, {'avg(Weight)': 3176.8, 'Year': 1975}, {'avg(Weight)': 3078.735294117647, 'Year': 1976}, {'avg(Weight)': 2997.3571428571427, 'Year': 1977}, {'avg(Weight)': 2861.8055555555557, 'Year': 1978}, {'avg(Weight)': 3055.344827586207, 'Year': 1979}, {'avg(Weight)': 2436.655172413793, 'Year': 1980}, {'avg(Weight)': 2532.1666666666665, 'Year': 1981}, {'avg(Weight)': 2453.548387096774, 'Year': 1982}]