user: Question: How many categories of new entries this round are there for the Fourth Round Proper? 
Columns: ['Round', 'Main date', 'Number of fixtures', 'Clubs', 'New entries this round', 'Prize money', 'Player of the Round']
Types: ['text', 'text', 'real', 'text', 'text', 'text', 'text']
Sample row: ['Extra Preliminary Round', '16 August 2008', 203.0, '761 → 558', '406: 356th–761st', '£750', 'n/a']
SQL:

assistant: SELECT COUNT("New entries this round") FROM "Table" WHERE "Round" = 'Fourth Round Proper';