CREATE TABLE table_203_457 (id DECIMAL, "tramway" TEXT, "country" TEXT, "city" TEXT, "height of pylons" TEXT, "span width , \ leaning straight line" TEXT, "span width , \ horizontal measurement" TEXT, "height of cable over ground" TEXT, "year of inauguration" DECIMAL, "notes" TEXT)

at least how many aerial tramways were inaugurated after 1970 ?
SELECT COUNT("tramway") FROM table_203_457 WHERE "year of inauguration" > 1970
SELECT COUNT("tramway") FROM "table_203_457" WHERE "year of inauguration" > 1970