The Hedonometer is a tool developed by the researchers Peter Dodds and Chris Danforth to gauge the valence of various corpora. Their index uses English Twitter data to calculate the level of positive valence in the English speaking world, which they call a sort of "Dow Jones Index of Happiness".
According to their data, 2020 was the least happy year to date. It has a yearly average 5.90. By contrast, the Hedonometer for the years 2009 to 2016 never fell below 6.00.
Historical data is available here.
Will the (English speaking) world be happier in 2021 than in 2020?
This question resolves positively if the year-long average Hedonometer for 2021 is greater than the year-long average for 2020.
Note: The Hedonometer tracks all Tweets in English, including from places that are not considered part of the "English-speaking world".