According to Pirelli overtaking increased in 2016 by more the 50 percent over the previous season.
In 2015 Pirelli calculated that there were 509 overtakes across the 19 races. This year that number rose to a whopping 826 overtakes from the 21 races. Interestingly though that isn’t quite as many as the last year of the V8 era in 2013, which had 985 overtakes across the season.
Pirelli classes an overtake as one that takes place on a complete flying lap (therefore not the first lap) – and is then kept all the way to the end of the lap. Any changes of position which are the result of major mechanical issues don’t count, and neither do those involving lapping and unlapping.
The Chinese Grand Prix had the most passes this year with 128 – the most in any single race since 1983 – while Hungary had the fewest with just 10. Of the wet races the Brazilian Grand Prix saw the most overtaking, with 64 passes.

So, why the increase? Apart from there obviously being more races this year, having two extra cars on the grid (Haas) no doubt helped, as did the number of times fast cars were out of position on the grid due to mechanical issues, penalties, or weather conditions in qualifying.
It’d be interesting to see how many of those passes were made with the aid of DRS though because let’s be honest, they’re not always particularly exciting, are they!