If we look at these results in isolation then the there's no dispute that the ratio has decreased, however, as I said google is constantly updating google scholar with new articles in different publisher years, so these numbers don't stay the same just because the year has passed. Choosing a specific year range is also somewhat arbitrary, if we chose to only look at 2005 to 2010 then I doubt either of us would say that the trend has shifted significantly. In the same way, if we expanded our search to 1990, or 1980 we might see that things go up and down over time as interest in the topic shifts and changes. It may just be the case that google doesn't have access to many sources in the early 2000s that use FGC, and that the ratio has always hovered between 4 to 1 or 3 to 1 and is not actually changing.