Years in dreams can complicated and are usually using the numerology system discussed in the themes section for numbers. The entire year becomes a numerical symbol for a state of mind or type of experience.
For example dreaming about being in the year 1800 may use the dream numerology system to reflect a high degree of freedom (18 = freedom of choice and 00 represents power).
If a person in a dream tells you that it’s the year 2012 than the symbolism is really saying that you are experiencing conflict that is difficult or impossible to confront (20 is powerful conflict and 12 is confrontation with conflict)
Other examples are 1999 which would mean the beginning of a big ending in your life 19+99. Or the year 1600 would be saying you are experiencing a time where you are processing negativity (16+00) and you are facing life situations that balance you (16=confrontation with negativity and 00 = power)
When you hear or see a year in your dream write it down and use the numerology system to decode it.
Years in dreams can also be symbols for what you think about that time period that is somehow symbolically connected to what is occurring in your life at the current moment