Below is the list of tables from the database along with their columns and datatype. Need to generate an accurate SQL query for the question.
Only use the columns present in the respective table. Only use the columns which are required to generate the SQL query. Only use table joins if required and not otherwise.

### Tables ###
TABLE: CREATE TABLE table_17378 ( "Index (Year)" text, "Author / Editor / Source" text, "Year of publication" text, "Countries sampled" real, "World Ranking (1)" text, "Ranking L.A. (2)" text )

### Question ###
how many countries sampled with year of publication being 2007 and ranking l.a. (2) being 7th

### Accurate SQL ###

SELECT COUNT("Countries sampled") FROM table_17378 WHERE "Year of publication" = '2007' AND "Ranking L.A. (2)" = '7th'