instruction: what was the three most frequently tested lab test until 2 years ago?
response: SELECT d_labitems.label FROM d_labitems WHERE d_labitems.itemid IN (SELECT t1.itemid FROM (SELECT labevents.itemid, DENSE_RANK() OVER (ORDER BY COUNT(*) DESC) AS c1 FROM labevents WHERE DATETIME(labevents.charttime) <= DATETIME(CURRENT_TIME(), '-2 year') GROUP BY labevents.itemid) AS t1 WHERE t1.c1 <= 3)