SemEval-2016 Task 4: Sentiment Analysis in Twitter
Table 10: Historical results for the best systems for Subtask A “Message Polarity Classification” over the years 2013–2016.
['[BOLD] Year', '[BOLD] 2013  [BOLD] Tweet', '[BOLD] 2013  [BOLD] SMS', '[BOLD] 2014  [BOLD] Tweet', '[BOLD] 2014  [BOLD] Tweet', '[BOLD] 2014  [BOLD] Live-', '[BOLD] 2015  [BOLD] Tweet', '[BOLD] 2016  [BOLD] Tweet']
We further look at the top scores achieved by any system in the period 2013–2016. Interestingly, the results for a test set improve in the second year it is used (i.e., the year after it was used as an official test set) by 1–3 points absolute, but then do not improve further and stay stable, or can even decrease a bit. This might be due to participants optimizing their systems primarily on the test set from the preceding year.