#4 Scoring 91 goals in a calendar year

Heralded as perhaps Lionel Messi's greatest ever achievement, in 2012 he managed to score 91 goals over the course of 12 months.
The Argentine Maestro managed to break Gerd Muller's decades-old record of 85 by a total of 6 goals.
This record arguably represents Messi at his peak and also Barcelona's peak, with many regarding the latter as the greatest team of all time.
Although Cristiano Ronaldo is a goal-scoring machine, he has never managed to score these many goals in a calendar year, even at the peak of his powers.
With Ronaldo failing to score 50 goals for the first time in years in 2018, it seems highly unlikely that he will be able to get close to Messi's total of 91.
Therefore, it seems that this record will never be broken by Ronaldo.