What is the % (1960) of Troms, which has a % (2040) smaller than 100 and a % (2000) smaller than 4.7?
CREATE TABLE "historical_population" (
  "rank" text,
  "county" text,
  "pct_1960" real,
  "pct_2000" real,
  "pct_2040" real
);
SELECT SUM("pct_1960") FROM "historical_population" WHERE "pct_2040"<100 AND "pct_2000"<4.7 AND "county"='troms';