Looks like 1984 or 1985 according to HADCRUT 3 and 4:

http://www.woodfortrees.org/plot/gistemp...

Checking the annual figures for those years we have;

For 1984; 0.008C (HC3) and 0.015C (HC4)

and for 1985; -0.038C (HC3) and -0.027C (HC4)

So 1985 was the last full year with an average below that of 1951-1980, according to the Hadcrut data sets. All 27 years since then have been warmer.

I don't think this alone says anything about the current trend; it could have warmed since the baseline period and started to cool, but if this was the case, we would need another decade or two of data before we could make that conclusion. In my opinion, the underlying trend is still one of warming. Claims of cooling, based on just a few years of data, are not statistically significant and are premature at best.

The last year when the global average temperature was below the 1951 to 1980 mean of global average temperatures was 1976.

http://data.giss.nasa.gov/gistemp/graphs...

Actually, all this really says is that warming was happening at that time and that Earth has never cooled to such temperatures since. What is more significant is that the ten warmest years were all 1998 or later.

It says not much about the idea of global cooling. It could be cooling by a small amount per year, or be a long term cooling trend with fluctuations in each direction. If we are to go by the arguments made by certain climate alarmists, it could be warming and we would still have cooling because there is a long term process that is cooling the planet, but currently other factors are temporarily outweighing the long term process.

I think around 75 would be the lows for that period it rises then drops again around 85 Anything beyond 85 would be above the average 50-80

Feb 1994 (-0.01C) but they don't know specifically what the average temperature is suppose to be. If you're looking for an average of an average, then the data is too convoluted to draw a conclusion on exactly what year it was below normal ('51 - '80 average). Who was it that established the '51 - '80 average? Is it the same people who say it is warming?

What is climate science really sure of when it comes to what is normal?

There is nothing magical about 1951 to 1980. If you took 1997 to 1999 you would see cooling. In any event, it hasn't warmed much in the last 15 years. The real question, which your question is attempting to dodge, is why did their predictions fail so utterly. IMO, what that indicates is that the theory that CO2 caused the warming is flawed.

The year to year fluctuation has not infrequently been a sizable multiple of the decade by decade trend, so you aren't going to get very far arguing along such lines with people so aggressively dumb they cannot grasp the difference between 0 for 4 in one baseball game and a seasonal batting average.