In the last 10 completed seasons (ignoring last season) the team finishing in 20th position only needed 50 points or more in 5 of these seasons.
In 2011-12 the team in 20th place got 50 points but only needed 45 as the team in 21st place only got 44.
In 2012-13 51 49 48.
In 2013-14 50 48 47.
In 2015-16 50 47 46.
The average points needed for a 20th place finish in the 10 year period was 48.8 points.
When we won division 2 in 2015-16 we had 99 points but we only needed 87 as Oxford in 2nd place got 86.
The team finishing in 20th position only NEEDED 50 points, but what total did they actually get.
Rerun your numbers with the team 20th place actually got and see what you get.