你看是这个意思吗？（以SQL为例）：

SELECT a.id
        ,c.date
        ,(CASE WHEN a.num<0 THEN 1 ELSE 0 END + CASE WHEN b.num<0 THEN 1 ELSE 0 END + CASE WHEN c.num<0 THEN 1 ELSE 0 END) / 3 AS num1
FROM TABLE AS a
        JOIN TABLE AS b
                ON b.date = a.date + 1
                AND b.id = a.id
        JOIN TABLE AS c
                ON c.date = b.date +1
                AND c.id = b.id;

如果你的数据中有些年份是缺失的话要改成LEFT JOIN

谢谢，一会看看