stats with seperate background process stats info:

 writes | walwriter_writes | backend_writes | dirty_writes | walwriter_dirty_writes | backend_dirty_writes | write_blocks | walwriter_write_blocks | backend_write_blocks | write_time | walwriter_write_time | backend_write_time | sync_time | walwriter_sync_time | backend_sync_time |          stats_reset
--------+------------------+----------------+--------------+------------------------+----------------------+--------------+------------------------+----------------------+------------+----------------------+--------------------+-----------+---------------------+-------------------+-------------------------------
 256004 |         14223300 |      439408129 |            0 |                      0 |                65933 |      3018749 |              287733552 |           1756612506 |          0 |                    0 |                  0 |         0 |                   0 |                 0 | 2017-09-12 19:21:03.103784+10
(1 row)


stats with background info with IO time:

 writes | walwriter_writes | backend_writes | dirty_writes | walwriter_dirty_writes | backend_dirty_writes | write_blocks | walwriter_write_blocks | backend_write_blocks | write_time | walwriter_write_time | backend_write_time | sync_time | walwriter_sync_time | backend_sync_time |          stats_reset
--------+------------------+----------------+--------------+------------------------+----------------------+--------------+------------------------+----------------------+------------+----------------------+--------------------+-----------+---------------------+-------------------+-------------------------------
 458362 |         27245324 |      881576768 |            0 |                      0 |                65933 |      3551641 |              304509489 |           2767649450 |          0 |                    0 |                  0 |   3366091 |           173043798 |        5855747060 | 2017-09-12 19:21:03.103784+10
(1 row)


stats info with combined background process info:

 walwriter_writes | backend_writes | walwriter_dirty_writes | backend_dirty_writes | walwriter_write_blocks | backend_write_blocks | walwriter_write_time | backend_write_time | walwriter_sync_time | backend_sync_time |          stats_reset
------------------+----------------+------------------------+----------------------+------------------------+----------------------+----------------------+--------------------+---------------------+-------------------+-------------------------------
         11954325 |      405757691 |                      0 |                68887 |              296636494 |           1623566649 |                    0 |                  0 |                   0 |                 0 | 2017-09-12 20:25:02.045657+10
(1 row)


stats info with combined background process info and IO time:

 walwriter_writes | backend_writes | walwriter_dirty_writes | backend_dirty_writes | walwriter_write_blocks | backend_write_blocks | walwriter_write_time | backend_write_time | walwriter_sync_time | backend_sync_time |          stats_reset
------------------+----------------+------------------------+----------------------+------------------------+----------------------+----------------------+--------------------+---------------------+-------------------+-------------------------------
         25846285 |      844341893 |                      0 |                68887 |              314435932 |           2626574325 |                    0 |                  0 |           190245460 |        5804902755 | 2017-09-12 20:25:02.045657+10
(1 row)