How many countries has a gdp (nominal) of $29.9 billion?
CREATE TABLE table_17188 (
    "Country" text,
    "Population" real,
    "Area (km\u00b2)" real,
    "GDP (nominal)" text,
    "GDP per capita (nominal)" text
)
SELECT COUNT("GDP per capita (nominal)") FROM table_17188 WHERE "GDP (nominal)" = '$29.9 billion'
Below are sql tables schemas paired with instruction that describes a task. Using valid SQLite, write a response that appropriately completes the request for the provided tables. ### Instruction: How many countries has a gdp (nominal) of $29.9 billion? ### Input: CREATE TABLE table_17188 (
    "Country" text,
    "Population" real,
    "Area (km\u00b2)" real,
    "GDP (nominal)" text,
    "GDP per capita (nominal)" text
) ### Response: SELECT COUNT("GDP per capita (nominal)") FROM table_17188 WHERE "GDP (nominal)" = '$29.9 billion'