Tier 1+2 Process Safety Events: The number of Tier 1 and 2 operational process safety events has been decreasing as following: 2012: 100 (Tier 1), 300 (Tier 2); 2013: 60 (Tier 1), 240 (Tier 2); 2014: 50 (Tier 1), 200 (Tier 2); 2015: 45 (Tier 1), 170 (Tier 2); 2016: 35 (Tier 1), 75 (Tier 2); 2017: 50 (Tier 1), 120 (Tier 2); 2018: 25 (Tier 1), 85 (Tier 2) (stacked bar)