There have been six higher fourth-innings scores than Babar Azam's epic 196 against Australia in Karachi last week. All of them were over 200, the highest being George Headley's 223 for West Indies against England in Kingston in 1929-30 (that match was also drawn).
Pat Cummins declined make Pakistan bat again despite Australia's lead of 408 in Karachi last week. The highest lead of all which did not result in the follow-on being enforced remains 563, by England (849) against West Indies (286) in Kingston in 1929-30; England's captain Freddie Calthorpe eventually set West Indies 836 to win. There was some excuse for this, as it was a timeless match - although it was left drawn in the end after nine days (the last two were rained off) since England had to catch the boat home!
India's consistent effort in their innings of 574 for 8 in Mohali - when the lowest score from the top eight was Shreyas Iyer's 27 - comes in third on this particular list. When Australia made 695 against England at The Oval in 1930, the lowest score among the top eight was Alan Kippax's 28. But when India amassed 664 against England at The Oval in 2007, the lowest was Wasim Jaffer's 35 (No. 8 Anil Kumble made 110 not out - his only century, in his 118th Test).
In that strange run-soaked match in Kolkata last week, Jharkhand made 880 in their first innings - when the biggest partnership was 191 for the tenth wicket - and, after dismissing Nagaland for 289, batted again and had reached 417 for 6 by the end of the match. That meant they were leading by 1008 - and they were the first team to lead by a four-figure amount in any first-class match. The previous record was 958, by Bombay (651 and 714 for 8 declared) in their Ranji semi-final against Maharashtra (407 and 604) in Poona (now Pune) in 1948-49.
You're right that only seven men reached four figures in first-class matches last year in England: Tom Haines of Sussex led the way with 1176 (and Derbyshire's Matt Critchley scored exactly 1000). Two of the others, Jake Libby (1104 runs) and Rory Burns (1038) played 15 matches: in 2006, Mark Ramprakash played 15 first-class games and piled up 2278 runs at an average of 103.54. In 1990, Graham Gooch scored 2746 runs in 18 first-class matches, averaging 101.70. The most in a season overall since 1968 - when the number of County Championship games began to be reduced - is 2755, by Jimmy Cook in 24 matches for Somerset in 1991.
Steven Lynch is the editor of the updated edition of Wisden on the Ashes