Submarine size comparison, top to bottom, left to right: US Seawolf-class SSN, Virginia-class SSN, Ohio-class SSBN, soviet/russian Kilo-class SSK, german Type 212 class SSK, Type 209 class SSK, and the monstrous soviet/russian Akula (AKA Typhoon) class of SSBN.
This includes the ranking compared to last year’s top 50, and the date at which both characters in the ship had first all appeared in that fandom. The colouring on the dates is white for the last two years (Jul 2013 onwards), light blue for 2-5 years ago (2010-2013), mid blue for 5-10 years ago (2005-2010) and dark blue for more than 10 years ago (pre-2005).
Older ships tend to have slipped down the list, as you can see from this graph, which shows a logarithmic relationship (R^2 = 24%) between the change in rank since 2014 and the years since the characters were created:
For the plaintext version of this data, check below the cut.