My theory is that by ‘71, ‘72, ‘73 companies figured out how to record live shows economically, and with good results. They learned from Woodstock and Altamont. That Rolling Sones truck thing just outside and all that. Or similar. CSNY. Uriah Heep Live. Yessongs. Bowie. Wishbone Ash. And so many others. I have some live albums from the sixties, but the only one I think is ok is an Association album. So I think we have Woodstock and the Stones for really starting the live album era. By ‘76, everyone was releasing live albums. Frampton being the king.