Postgres 12

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create table the_table ("2017" int, "2018" int, "2019" int, "2020" int);

CREATE TABLE

insert into the_table
values
(358, 1300  , 973   , 101   );

INSERT 0 1

select x.year, x.count
from the_table t
  cross join lateral (
      values ("2017", 2017), ("2018", 2018), ("2019", 2019), ("2020", 2020)
  ) as x(count, year);

year
count

2017
358

2018
1300

2019
973

2020
101

SELECT 4