what is the highest % hydropower when % coal is 4.9 and % nuclear power is more than 0?
CREATE TABLE "production_and_source" (
  "country" text,
  "electricity_production_kw_h_billion" real,
  "pct_coal" real,
  "pct_natural_gas" real,
  "pct_oil" real,
  "pct_hydropower" real,
  "pct_other_renewable" real,
  "pct_nuclear_power" real
);
SELECT MAX("pct_hydropower") FROM "production_and_source" WHERE "pct_coal"=4.9 AND "pct_nuclear_power">0;