Table schema:
CREATE TABLE table_29289372_1 (population__2010_ VARCHAR, income_classification VARCHAR, city_municipality VARCHAR)

Question: When itogon, benguet is the city/municipality and 1st class is the income classification how many measurements of population in 2010?
SQL: SELECT COUNT(population__2010_) FROM table_29289372_1 WHERE income_classification = "1st Class" AND city_municipality = "Itogon, Benguet"