DC metro use

     DC metro use is fluctuated during day, especially each hour. There are two spikes in 8:00 and 18:00 while three dips in 6:00, 16:00 and 20:00. The number of people who use DC metro rises significantly to around 400, reaching the highest point during day shortly after 8:00. On the other hand, the number of people who use DC metro declines to less than 100, reaching the lowest point during day shortly after16:00. These fluctuations seem to be caused mainly by the office workers because the time of two spikes is correlated with opening and closing time of the general office.