when did they go to electronic ignition?

OK here is what I got from the sun cards they are 99% right usually. 72 all slants are P(points) E (Electronic) came in in 73
all these are 72
340- 240 hp are E
360- 175 hp are P
400- 190, 225, and 265 hp are P
440 -225 hp are P
440- 280. 290hp and six pack are E

73 all electronic. 71 all point, now there are the special orders like MP and dual point options to consider these are the stock production years. Hope it helped. Good question though. I knew 72 was the crossover just did not know exactly what and when.