The table gives a nation's government outlays and tax revenues for 2015 through 2019. 

                 

Year	Government outlays     (trillions of 2012 dollars)	Tax revenue     (trillions of 2012 dollars)
2015	0.75	0.80
2016	0.80	0.83
2017	0.87	0.86
2018	0.95	0.95
2019	1.06	1.02

During which years did the country have a budget deficit?