single-line line chart, prices against years
2-lines line chart, red for retail price, green for farm price, y axis starts from 0, time axis un-alingned
moved code for 2-line line charts to separate js file; displayed line chart matrix in main html;
put line charts into columns;
aligned time line for small multiples;
added csv data files; trimmed years for individual foods; interpolated missing values for pears;
added percentage line chart; switch back and forth using a button;
changed line colors;
added time axes; cleaned up axes and label;
share common svg;
added rule; put style in css file;
four rules;
added data labels that move with rules in the x direction; need to move them in the y direction also;
highlight current rule;
changed rule opacity;
fixed data label bug;
can print data label for each line chart correctly; need to adjust the y position;
adjusted y pos of retail data labels; need to fix years with missing data;
fixed data labels for years with missing data; need to code data labels for farm;
added data labels for farm prices; need to do the same for percentages;