Hi.

In the VF I used the date format as YYYY-MM-dd in the 
<apex:outputText value="{0,date,YYYY/MM/dd}">
Before the last week of the year it was OK. When the new year falls in the  last week of Decemeber comes the issue.
For example
2014:
S   M  T  W Th F Sat
28 29 30 31 1   2 3

In the above calendar 1st Jan of 2015 falls in the Thurusday.So when I viewd the records of 28,29,30 of December 2014 It showed as
2015-12-28
2015-12-29
2015-12-30
2015-12-31

After that I came to know that
@"YYYY" is week-based calendar year.
@"yyyy" is ordinary calendar year.
http://realmacsoftware.com/blog/working-with-date-and-time

cheers
suresh