Among all the shipments to Florida, what is the percentage of the shipment to Jacksonville?
"Florida" is the state; "Jacksonville" is city_name;
SELECT CAST(SUM(CASE WHEN T2.city_name = 'Jacksonville' THEN 1 ELSE 0 END) AS REAL) * 100 / COUNT(*) FROM shipment AS T1 INNER JOIN city AS T2 ON T1.city_id = T2.city_id WHERE T2.state = 'Florida'