CREATE TABLE table_7110 ("Year" FLOAT, "Conventional plans" CLOB, "HMOs" CLOB, "PPOs" CLOB, "POS plans" CLOB)

How many years have HMOs been 27% and POS plans 18%?
SELECT COUNT("Year") FROM table_7110 WHERE "HMOs" = '27%' AND "POS plans" = '18%'
SELECT COUNT("Year") FROM "table_7110" WHERE "HMOs" = '27%' AND "POS plans" = '18%'