From the Introduction by Pamela Jackson and Jonathan Lethem
"The Exegesis, an unruly and unlikely "manuscript" that threatened to defy editorial ambition, remained terra incognita. Its first scholar, Jay Kinney, published a "Summary of the Exegesis Based on Preliminary Forays" in 1984. Estimating the document at two million words, Kinney defined requirements for its publication: transcription from the handwritten pages; an attempt at chronological resequencing; and "selecting out the most coherent portions." He rightly called this prospect "staggering." With Williams and a few volunteers, Kinney's venture at least accomplished the photocopying and inventory of the eight-thousand-plus pages."
David Gill told me that he estimates what was published as being about 10% of it. By the way, he just posted a new post about the Exegesis and other PKD readings/listenings/viewings