This article walks you through the ability to make a chart that visualizes data across multiple years over months or any other grouping for that matter. This is helpful when trying to see trends over time.
To start, you'll want to drag on the date attribute you'd like to analyze. In this example, we'll graph the number of homes for sale and graph by month and year. To see only the years for 2009-2010, as in the following example, you will want to change the filter on the date attribute.
After dragging on the date attribute, you will need to ensure that the aggregation (the first dropdown circled) reads SUM OF to visualize the number of homes for sale. To visualize the data by month and year, make sure to group by month of year and select year over year to see the period over period comparison.
Feel free to test this out by importing Quandl "Real Estate Stats" data with your DataHero account, or try it out with your own data.