Spreadsheet time - based only on significant coasters I've done, average rating out of 20:
Nice upwards trend there, a reason to look forward to the future.
Top 5, showing 2016 is my true winner, but dragged down by a lot of lesser stuff:
2015 - 16.25 (3 Jungle Trailblazers, Kärnan)
2014 - 15.2 (Helix, Alpina Blitz, Parrot Coaster)
2018 - 15.17 (Icon, Wood Express, Valkyria)
2016 - 14.69
(Python in Bamboo Forest, Taron, Flying Aces, Wildfire, Flying Dinosaur, Flash, Soaring with Dragon, Coaster through the Clouds, Lost Gravity)
2017 - 14 (DC Rivals, Arashi, Jungle Dragon)