I can't get a direct link, so you have to go here.
https://www150.statcan.gc.ca/t1/tbl1/en/cv.action?pid=1410028701
For geography, select Canada and Ontario. For reference period, select Jan 2018 to May 2019.
Looking at Ford: He was elected in early June - so I took the end of May numbers as the transition date.
In Canada, employment (seasonally adjusted) was 18603.7 at the end of May, 2018, and 19,056.8 at end of May, 2019 - a gain of 453.1k jobs.
In Ontario, employment was 7,215.8 at the end of May, 2018, and 7,438.0 at end of May, 2019 - a gain of 222.2k jobs.
Doing the math, the Rest-of-Canada (ROC) created 230.9k jobs.
222.2/230.9 = 96%. Ontario recreated 96% of the jobs that the ROC created.
Repeat for each PC, Liberal and NDP governments.
For population, I just used google and picked the year roughly in the middle of the mandate. It seems Ontario's population has increases from about 60% of ROC to 68% now. If the jobs created is larger than the population percentage, then the government is doing a good job.
This is about the best way I could think of to compare how well Ontario is doing. It works nicely since Ontario and ROC are roughly the same size. Otherwise, I think I would take jobs created per population somehow. It takes out of the equation the economic conditions, because it is a relative measure. If you just compare absolute jobs, then the Premier governing in a recession is punished, while those in a boom are rewarded.