What is the lowest value for 1960, when the value for 2000 is less than 8.4, when the value for 1950 is greater than 3.5, and when the value for 1990 is less than 3.3?
CREATE TABLE "share_of_global_gdp_ppp_pct" (
  "region" text,
  "1950" real,
  "1960" real,
  "1970" real,
  "1980" real,
  "1990" real,
  "2000" real
);
SELECT MIN("1960") FROM "share_of_global_gdp_ppp_pct" WHERE "2000"<8.4 AND "1950">3.5 AND "1990"<3.3;