This is confusing in the CSV format, but it makes much more sense on the SpyFu results page. Don’t let the zeros and “E+11” confuse you in the CSV format. The Ad Timeline graph is a helpful visual aid to give you an idea of a domain’s overall performance on a keyword. Here’s what it looks like in the actual on-page view.
We can’t recreate an image like this in the CSV file, so if you export, you will see it as a string of numbers. Don’t get caught up in trying to understand the numbers, especially if you can let the graph do the work for you.
However, if you only have access to the CSV files or you are just a Number Person, here’s a short version of the explanation. The numbers don’t correlate to actual rankings but to levels—high, mid and low. For example, an ad that ranked 2 out of 11 advertisers would show a high bar. The last number in the series correlates to the most recent month. A zero is where we do not show them advertising on that keyword for that month.