How many draw games happened on 2018/8/7 for National League?
National League is the name of division; Date = '2018-08-07'; draw refers to FTR = 'D'; games refer to Div;
SELECT COUNT(T1.FTR) FROM matchs AS T1 INNER JOIN divisions AS T2 ON T1.Div = T2.division WHERE T2.name = 'National League' AND T1.Date = '2018-08-07' AND T1.FTR = 'D'