WITH
InsuranceWithCounts AS (
SELECT
tiv_2016,
COUNT(*) OVER(PARTITION by tiv_2015) AS tiv_2015_count,
COUNT(*) OVER(PARTITION by lat, lon) AS city_count
FROM Insurance
)
SELECT ROUND(SUM(tiv_2016), 2) AS tiv_2016
FROM InsuranceWithCounts
WHERE tiv_2015_count > 1
AND city_count = 1;