I can't tell about the last 2 years, but this year, we have been suffering from a lot of FUD coming South Korea and then their the bitcoin future contracts expiration that has somewhat contributed to the price dipping further. Other says' because of the Chinese New year. Investor's cashing it out to celebrate that holiday.

Well its been a trend for the last 3 years but knowing bitcoin's volatile history, we can't really say for certain if this is a regular dip. Its almost end of the month, I hope things change for the better in February.