They mentioned “5 years before date of submission”. So if you will sign/submit February 26,2020 then the 5 years period start from February 26,2015 to February 26,2020.I didn't even mentioned for 2019 in my application, started from 2018,2017,2016,2015,2014
unless you applying in march and already filled 3 years taxes you are good to go, moreever after taxing 2019, your tax will be automatically updated on CRA data and CIC will access it during the process of your file as there is a column in application where we consent CIC to access Tax return data from CRA
If you still didn’t submit your 2019 tax, you can simply answer yes/No.
2014 is out of 5 years period .