Year	licenses	defects	lengths
1924	1.350	8	6
1925	1.960	8	6
1926	2.270	9	6
1927	2.483	10	6
1928	2.730	11	6
1929	3.091	11	7
1930	3.647	12	7
1931	4.620	16	7
1932	5.497	18	7
1933	6.260	19	8
1934	7.012	20	8
1935	7.618	21	8
1936	8.131	22	8
1937	8.593	23	8