CREATE TABLE table_203_717 (id NUMBER, "number" NUMBER, "year built" NUMBER, "livery" CLOB, "current status" CLOB, "notes" CLOB)

are the most trains operational or do they have another status listed ?
SELECT "current status" FROM table_203_717 GROUP BY "current status" ORDER BY COUNT(*) DESC LIMIT 1
SELECT "current status" FROM "table_203_717" GROUP BY "current status" ORDER BY COUNT(*) DESC FETCH FIRST 1 ROWS ONLY