Below is an attempt of ranking 'popularity' of programming languages invented in the 1980s or earlier by searching for "language programming" on worldcat. The table lists how many library items exist per year. C and C++, e.g., can unfortunately not be distinguished in this search, and there are also false positives, considering that C's first release year is 1972.
1970 1972 1974 1976 1978 1980 1982 1984 1986 1988 1990 1992 1994 1996 1998
Ada 0 0 0 2 0 0 0 0 0 22 141 140 145 185 258 244 384 439 562 736 452 658 389 279 263 141 91 57 37 31
Algol 16 15 16 11 9 13 17 19 13 11 7 12 2 9 4 2 4 0 1 0 1 0 0 0 0 1 0 1 0 0
APL 13 20 4 13 11 13 9 14 21 9 11 17 4 18 18 14 16 12 8 13 8 5 4 7 9 2 3 2 2 4
Assembly 7 2 2 0 4 3 3 4 6 5 4 9 3 15 17 15 12 14 8 11 10 9 12 7 11 12 6 12 9 10
AWK 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 2 5 8 3 5 7 3 3 5 9 7 4 5
BASIC 19 31 44 55 65 56 46 61 73 49 96 132 196 218 214 233 186 127 107 77 78 59 87 92 73 78 73 84 73 75
BCPL 0 0 1 1 2 1 1 1 5 2 1 1 0 1 0 0 0 0 0 0 0 0 1 0 0 0 0 0 0 0
Caml 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 2 1 1 0 0 1 2
COBOL 18 23 15 20 30 21 40 36 48 31 27 46 31 44 44 35 19 22 22 28 25 24 15 7 18 9 16 42 11 14
COMAL 0 0 0 0 0 0 0 1 0 0 0 0 0 0 0 0 0 0 1 1 0 0 0 0 0 0 0 0 0 0
C 9 12 11 11 13 23 20 27 38 27 30 48 73 83 130 170 196 278 265 259 370 352 376 498 517 582 465 469 513 392
Eiffel 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 3 2 1 2 1 4 4 5 4 7 1 2 1
Forth 0 0 0 1 0 0 0 1 0 0 1 2 8 12 11 11 12 13 3 9 7 5 2 2 8 1 1 0 2 2
FORTRAN 65 63 60 56 59 69 72 91 79 64 60 48 55 44 73 72 68 55 49 81 39 43 38 36 46 36 30 29 20 17
FoxPro 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 2 1 3 3 1 3 2 3 1 1
Lisp 3 10 9 14 17 16 20 26 19 16 26 38 23 26 54 57 73 94 46 76 72 43 33 37 31 17 17 8 11 6
Logo 0 2 2 5 4 0 0 0 1 1 3 1 3 36 57 37 59 30 36 32 51 31 25 20 23 29 19 16 21 19
MIMIC 1 0 2 1 5 0 0 0 0 0 0 2 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
ML 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 0 1 0 0 1 2 7 9 14 1 9 10 11 16
Modula-2 0 0 0 0 0 0 0 0 0 0 0 0 5 5 3 14 12 13 9 12 9 8 3 1 9 1 0 0 0 0
Modula-3 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 0 1 0 1 1 2 0 1 0
Oberon 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 5 8 5 1 5 6 3 4 2 2 0
Occam 0 0 0 0 0 0 0 0 0 0 0 0 0 2 11 6 11 20 35 19 19 19 13 15 11 8 8 2 4 5
Pascal 0 0 0 2 15 6 19 13 34 30 56 60 62 128 90 109 101 125 105 98 99 85 60 68 46 32 28 17 24 15
Perl 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 4 0 3 9 14 30 37
PL-11 0 0 0 0 1 0 1 0 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
PL/C 0 0 0 2 4 0 1 0 1 0 2 0 1 0 1 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0
PL/I 7 17 16 16 15 9 7 10 15 8 5 6 13 3 3 6 2 2 2 0 1 2 0 0 2 1 0 1 1 0
Postscript 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 2 9 0 6 5 3 0 0 1 1 1 0 1
Prolog 0 0 0 0 0 0 0 1 0 1 0 4 8 12 31 43 77 89 68 53 70 62 44 71 43 22 30 16 17 9
REXX 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 3 1 0 1 0 4 1 3 5 5 3 2 2 2 0
Scheme 0 0 0 0 0 2 0 0 2 0 0 0 0 0 4 3 4 4 2 2 10 16 5 2 6 6 11 8 4 6
sed 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 2 0 0
Simula 0 0 0 0 3 6 3 2 2 9 14 3 4 0 0 0 0 1 3 0 0 0 0 0 2 0 0 1 0 0
Smalltalk 0 0 0 0 0 1 0 3 0 0 0 0 2 2 4 6 3 8 4 8 6 12 5 14 20 19 11 6 9 12
tcl 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 3 1 2 2