This is the plot of top 5 popular start stations of citibike from 2013-08 to 2014-08. Bsed on this plot, we can observe the variation of bike usage over stations.

## 'data.frame':    65 obs. of  7 variables:
##  $ start.station.visit: num  9874 9721 9631 9253 9020 ...
##  $ startstationname   : Factor w/ 9 levels "8 Ave & W 31 St",..: 3 6 7 9 5 7 6 3 5 1 ...
##  $ end.station.visit  : num  10554 9599 9450 9076 7929 ...
##  $ endstationname     : Factor w/ 10 levels "8 Ave & W 31 St",..: 3 8 10 5 1 3 8 10 1 5 ...
##  $ year               : num  2013 2013 2013 2013 2013 ...
##  $ month              : num  8 8 8 8 8 9 9 9 9 9 ...
##  $ yearmonth          : chr  "2013-08" "2013-08" "2013-08" "2013-08" ...