wikiadmin@10.64.32.76(enwiki)> select count(*), SUBSTR(page_links_updated, 1,6) from page group by SUBSTR(page_links_updated, 1,6) order by SUBSTR(page_links_updated, 1,6) desc;
+----------+---------------------------------+
| count(*) | SUBSTR(page_links_updated, 1,6) |
+----------+---------------------------------+
|  6964188 | 202012                          |
|  7726365 | 202011                          |
|  6393815 | 202010                          |
|  3628545 | 202009                          |
|  1647340 | 202008                          |
|  1126647 | 202007                          |
|   714094 | 202006                          |
|  2107616 | 202005                          |
|  1458445 | 202004                          |
|  1199835 | 202003                          |
|   916622 | 202002                          |
|   918132 | 202001                          |
|  1119428 | 201912                          |
|   933069 | 201911                          |
|  1250997 | 201910                          |
|  1032874 | 201909                          |
|   901646 | 201908                          |
|   226159 | 201907                          |
|   788871 | 201906                          |
|   137171 | 201905                          |
|   199202 | 201904                          |
|   129178 | 201903                          |
|   111255 | 201902                          |
|   137766 | 201901                          |
|   153427 | 201812                          |
|   216029 | 201811                          |
|   120998 | 201810                          |
|   130087 | 201809                          |
|   252573 | 201808                          |
|   108601 | 201807                          |
|    99768 | 201806                          |
|    96349 | 201805                          |
|   101527 | 201804                          |
|   114136 | 201803                          |
|   107578 | 201802                          |
|   110890 | 201801                          |
|   411536 | 201712                          |
|   112077 | 201711                          |
|   142440 | 201710                          |
|   119278 | 201709                          |
|    91605 | 201708                          |
|    73906 | 201707                          |
|   178767 | 201706                          |
|    80626 | 201705                          |
|   227609 | 201704                          |
|   278242 | 201703                          |
|    90560 | 201702                          |
|   106757 | 201701                          |
|   175753 | 201612                          |
|   154895 | 201611                          |
|    80514 | 201610                          |
|    77041 | 201609                          |
|   192573 | 201608                          |
|    70651 | 201607                          |
|    81924 | 201606                          |
|    86403 | 201605                          |
|    87858 | 201604                          |
|    76180 | 201603                          |
|   105700 | 201602                          |
|    81511 | 201601                          |
|    70803 | 201512                          |
|    78226 | 201511                          |
|    81578 | 201510                          |
|    74509 | 201509                          |
|    83020 | 201508                          |
|    75405 | 201507                          |
|    94532 | 201506                          |
|   196016 | 201505                          |
|   577114 | 201504                          |
|    73891 | 201503                          |
|    70661 | 201502                          |
|    66575 | 201501                          |
|    75643 | 201412                          |
|    70189 | 201411                          |
|    83745 | 201410                          |
|    62655 | 201409                          |
|   239959 | 201408                          |
|   177983 | 201407                          |
|    67779 | 201406                          |
|    79420 | 201405                          |
|    69650 | 201404                          |
|    78283 | 201403                          |
|    69570 | 201402                          |
|    58596 | 201401                          |
|     1200 | 201312                          |
|     1035 | 201311                          |
|     1024 | 201310                          |
|      788 | 201309                          |
|     1016 | 201308                          |
|      881 | 201307                          |
|      935 | 201306                          |
|     1047 | 201305                          |
|     2247 | 201304                          |
|     3544 | 201303                          |
|      831 | 201302                          |
|     1306 | 201301                          |
|      752 | 201212                          |
|      818 | 201211                          |
|      724 | 201210                          |
|      678 | 201209                          |
|      710 | 201208                          |
|      935 | 201207                          |
|      888 | 201206                          |
|      606 | 201205                          |
|      515 | 201204                          |
|      761 | 201203                          |
|      741 | 201202                          |
|      881 | 201201                          |
|      901 | 201112                          |
|     1354 | 201111                          |
|      915 | 201110                          |
|     1673 | 201109                          |
|     1105 | 201108                          |
|     1099 | 201107                          |
|      709 | 201106                          |
|      516 | 201105                          |
|      566 | 201104                          |
|      693 | 201103                          |
|      622 | 201102                          |
|      549 | 201101                          |
|      571 | 201012                          |
|      438 | 201011                          |
|      511 | 201010                          |
|      355 | 201009                          |
|      500 | 201008                          |
|     1437 | 201007                          |
|      377 | 201006                          |
|      344 | 201005                          |
|      291 | 201004                          |
|      366 | 201003                          |
|      260 | 201002                          |
|      370 | 201001                          |
|        1 | 200903                          |
|        3 | 196912                          |
|  2825653 | NULL                            |
+----------+---------------------------------+
135 rows in set (36.29 sec)