Short answer: about ~70% of the time.
Over roughly the last 100 years, the Liberal Party of Canada has formed the federal government for around 65–70 years, making them by far the most frequent governing party in Canada.
Big-picture breakdown (approximate)
From 1921 to today:
Liberals: ~65–70 years in government
Conservatives (including Progressive Conservatives): ~30–35 years
Others (CCF/NDP, etc.): 0 years forming federal government
Why the Liberals dominate
A few structural reasons:
They’ve often positioned themselves as a centrist “broker” party, able to absorb swings left or right
They tend to recover faster after losses than Conservatives
Conservatives have historically split (PC vs Reform/Alliance) which cost them power for long stretches
Long uninterrupted Liberal runs (e.g. Mackenzie King and Trudeau era) heavily skew the numbers
Notable long Liberal stretches
1921–1930 (King)
1935–1957 (King + St-Laurent)
1963–1984 (Pearson + Pierre Trudeau, with brief interruption)
1993–2006 (Chrétien + Martin)
2015–present (Justin Trudeau)
If you want, I can:
Break it down year-by-year
Compare popular vote vs time in power
Or show how this compares to other democracies (UK, US, Australia)