1911 Census of England and Wales, General Report with Appendices, Table 131: " Proportions per 1,000 persons at each Age-Group speaking Welsh only, 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 130 97 60 46 62 126 224 85 151
                 
Monmouthshire (including County
    Borough)
3 2 2 3 4 7 15 4 7
  Monmouth Administrative County 3 3 3 3 5 9 18 5 9
  Newport County Borough 1
Glamorganshire (including County
    Boroughs)
46 27 18 18 25 54 100 31 66
  Glamorgan Administrative County 60 34 23 22 31 71 131 39 91
  Cardiff County Borough 2 1 1 1 1 2 5 2 2
  Merthyr Tydfil County Borough 39 20 17 22 29 68 140 35 73
  Swansea County Borough 24 16 11 12 13 32 64 19 33
Anglesey 602 507 296 247 299 400 540 362 480
Brecknockshire 109 67 41 28 41 70 119 56 93
Cardiganshire 599 490 271 177 240 421 593 342 504
Carmarthenshire 402 267 147 107 151 284 436 205 356
Carnarvonshire 578 496 305 225 289 410 542 356 477
Denbighshire 200 126 62 57 70 135 230 101 183
Flintshire 79 34 16 16 22 46 104 34 75
Merionethshire 667 574 316 208 264 437 566 367 506
Montgomeryshire 204 151 81 66 82 116 185 107 156
Pembrokeshire 157 103 51 37 54 99 169 77 119
Radnorshire 3 1 2