Google Trends is a useful tool to compare the trends in what is being searched on Google. I was curious to see what PHP frameworks are being searched ( and used) on Google. The image above shows that Cakephp is the most popular framework while Code Igniter/Kohana are trailing behind. But Code Igniter started relatively late (late 2006) as compared to other frameworks (mid to late 2005) but has been picked up quickly.
Another interesting observation from the above trend is, Code Igniter is most popular in Bangladesh, Indonesia and Philippines. I wonder if there is a way to get trends of jobs for these frameworks.