The 'decade' of the 1920s runs from January 1, 1920 to December 31, 1929.
There have been a lot of changes during/in/over the past two 'decades'.
a 'decade' of drought [=a drought that lasted 10 years]
(..) Let's get into how you calculated all those parameters. There was no time for calculating. I have relied on my experience on managing the altitude and speed on thousand of flights over four decades. You say you didn't calculated... I attempted. - You attempted. Yes. And I bet my life on it. (..)2016 Sully