2.4. Accident frequency calculation
The exposure during the period 1990–2014 has been 3390 ships years and is used for the accident frequency calculations. Based on the ships and accident statistics the frequency is calculated as the fraction of accident per accident type and the total number of accidents. All accidents in the consideration were noticeable accidents with influence on cruise market. However, the number of accidents with fatalities is too few to represent any significant accident trend. Table 3 is divided in two periods, mainly to demonstrate the most relevant changes of accident frequencies per type of accident during two-year periods.