Hello! Project released a statement on why they are pushing to release more songs digitally for H!P's future while still releasing CDs as usual.
Each H!P group releases 2 to 3 CD singles a year up until now. But to make things even more fun, they want to try new methods of releasing a variety of songs digitally by music download and video download even more. This will allow them to experiment with songs not seen in the usual CD releases. They can create solos, shuffle units and have H!P OG members in these songs too. Each H!P group will continue to releases CDs as usual, but they will now release a various types of songs digitally that is especially made for live tours as early as possible.
below is list of songs recently released for download
http://www.helloproject.com/news/7429/