<Attribute info>

ticks >>> input the values of max tick and min tick, 
          then the ticks will be automatically generated by bullet.js

startPoints >>> each bullet chart consists of multiple color bars,
                each value in "startPoints" means the start point of each color bar.
* the first startPoint is always 0

widths >>> each color bar has its own width, 
           each value in "widths" define the width of the color bar. 
* the sum of all width should be 760
