To get the whole year, for example "2015" , from site.time you can use:
{{ site.time | date: '%Y' }}
To just get the last 2 digits from 2015, this will lead to the output of "15" :
{{ site.time | date: '%y' }}
5ervant Dec 03 '15 at 15:50 2015-12-03 15:50
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