Less House Seller in December?

I am still looking for my "targeted" flat at Jurong West area. However it seems to be getting more and more difficult as i notice that there are less seller listing their unit for sale in December. It is based on the number of posting appear on the housing website for example the propertyguru.com.sg and the iproperty.com.sg . 

I am curious, it there a trend whereby unit owners are less willing to let go their unit at the end of the year? Or it is purely affected by the economy as in the price of the unit etc?Or it is because most of the property agents are on vacation after bagging enough money for the past 11 mths.  

Is there any website in singapore whereby owners can put their unit on sale? 

The shopping for this X-Mas would be My Dream Unit. It seems difficult to get the unit that you like than what i initially thought of. However, from discussion with friends who had bought their units, in average buyers roam around 20++ units before they settle down with their unit. If that applies to me as well, that means i would find my very soon ;)