Our mobile app has a three-step card application flow: start application, submit documents, and activate the card. The event log has one row per event, with the user, the event name, and the timestamp. For example, user A started on March 1, submitted on March 2, and activated on March 5, while user B only has a submit event on March 3 and no start event. Write a SQL query that counts how many users completed each step in the correct order.

手机App上的开卡流程有三步：开始申请、提交资料、完成激活。事件日志每一行记录了用户、事件名称和发生时间。比如用户A在3月1日开始、3月2日提交、3月5日激活；用户B只有一条3月3日的提交记录，没有开始记录。请你写SQL，统计按顺序走到每一步的人数。