Biggest drop in sales in a game series?

[TruckOSaurus]

1	Nintendogs	DS	2005	Simulation	Nintendo	9.05	10.93	1.93	2.75	24.66
2	Nintendogs + cats	3DS	2011	Simulation	Nintendo	1.39	1.17	0.72	0.26	3.54

I don't think anymore mentioned it yet. I'd blame the cats here, cats are lame.