I'm not sure that per capita is a very useful rubric to measure over time. Like I'm not saying there's no relation to population size, if you compare a tiny country to a large one, but it's not clear to me that there's a strong relationship - why a government would be expected to lock up 5% more journalists if the population grew by 5%. Or why if a country of 30 million jailed 100 journalists it should be necessarily be considered less repressive than if a country of 40 million jailed 100.