2012-2018 growth around 15%, 2019 almost no hiring, but still growing (meltdown), 2020 catch-up hiring, and forecast continued growth at 15%.
Bases are not very different for seniority, at least from my position. Not a lot of people leaving.
I would guess 50% as an FO, so 25% total would get you a good hard line: between 1-2 years.
Upgrade, count on doubling in size, so 5-6 years.
Could be faster or slower so FWIW.