The graph probably shows the AVERAGE attendances. Home Attendances over 30,000:
36,747 v Fulham 7.12.58
35,000 v Chelsea 18.2.67
34,766 v Rochdale 3.5.72
33,500 v Derby County 26.10.76
33,300 v Crystal Palace 24.2.76
33,431 v Blackpool 29.4.78
32,979 v Southampton 2.1.78
32,647 v Tottenham...