There are some records whose week_start_date are yyyy-01-01 but weekofyear are set 52 or 53.
sj, 1993, 53, 1993-01-01
sj, 1994, 52, 1994-01-01
sj, 1995, 52, 1995-01-01
Therefore, (a) the data sorted by (year and weekofyear) pair, and (b) the data sorted by (week_start_date) have different order.
Can I assumes that the data sorted by (week_start_date) have right order?