1911 Census of England and Wales, General Report with Appendices, Table 132: " Proportions per 1,000 persons at each Age-Group speaking both English and Welsh, 1911; and proportion at all ages, 1901 and 1911: in Administrative Counties and County Boroughs".

COUNTIES AND COUNTY BOROUGHS. AGES. TOTAL,
3 years and
upwards.
3-5. 5-10. 10-15. 15-25. 25-45. 45-65. 65
and
upwards.
1911. 1901.
Wales and Monmouthshire 174 265 337 360 378 403 378 350 348
                 
Monmouthshire (including County
    Borough)
30 39 47 61 107 176 221 92 123
  Monmouth Administrative County 36 47 57 74 127 213 258 111 148
  Newport County Borough 5 5 8 16 34 47 79 26 36
Glamorganshire (including County
    Boroughs)
210 284 323 343 374 421 414 350 369
  Glamorgan Administrative County 254 347 399 422 450 509 487 424 457
  Cardiff County Borough 13 28 37 44 71 116 161 65 79
  Merthyr Tydfil County Borough 287 375 428 463 497 565 541 467 498
  Swansea County Borough 122 167 199 239 268 337 366 252 291
Anglesey 167 359 579 643 593 509 404 526 437
Brecknockshire 170 258 308 327 379 466 494 359 366
Cardiganshire 195 401 654 690 646 492 352 554 426
Carmarthenshire 325 571 729 730 691 602 477 644 548
Carnarvonshire 184 356 577 635 554 456 349 500 419
Denbighshire 233 374 477 502 498 496 440 466 436
Flintshire 200 293 334 377 414 467 473 388 416
Merionethshire 144 318 611 697 626 476 365 536 431
Montgomeryshire 114 214 319 346 377 401 378 341 319
Pembrokeshire 91 168 234 246 277 279 279 247 225
Radnorshire 20 12 19 36 64 78 112 53 60