SELECT SUM("Silver") FROM table_9940 WHERE "Nation" = 'japan' AND "Total" < '1'
what is the silver when the nation is japan and the total is less than 1?
CREATE TABLE table_9940 (
    "Rank" text,
    "Nation" text,
    "Gold" real,
    "Silver" real,
    "Bronze" real,
    "Total" real
)