The line graph shows the number of vacancies for accountants in a certain company from 2011 to 2017. The corresponding vacancy data points are: 2011: 40, 2012: 60, 2013: 30, 2014: 10, 2015: 50, 2016: 40, 2017: 70.
In which year were the number of vacancies lesser than that of the previous year?
