Global PC shipments are down considerably over that span (2019 was the first year of overall market growth in nearly a decade), so it isn't so much that Apple has sold more as it may be that they're holding on better than other manufacturers. One quick result from a Google search shows they have 7.9% of the global PC market, at least for one particular quarter in 2019. I couldn't find a good chart with Mac shipments, but one that showed revenue looked fairly flat over the last decade (or at least the part of it the chart included), but it's hard to tell due to all of the other data being included. If we really wanted to know we could dig through financial reports I suppose since they have to report revenue at the very least.Alternately, Macs seem to represent ~15% of active laptops/desktops connecting to the internet:
This graph shows the market share of desktop operating systems worldwide based on over 5 billion monthly page views.gs.statcounter.com
10 years ago it was only about 5%, so significant growth.
There is also significant regional split.
Lower in Asia, Africa, South America, and India. (near 10%)
Higher in Oceana, and North America. (near 30%).
Europe in between. (near 20%)
The regional breakdown just shows that countries that are more well off financially buy more Macs. Not exactly rocket science, but unless Apple is willing to lower their prices (which is unlikely for a variety of reasons) there's always going to be a cap on the amount of hardware that they can sell. From the perspective of maximizing profit, the additional sales they would get from a price cut aren't likely to make up for the lost profit of the higher sale price. Never mind that they would likely need to invest some initial capital to increase their production capacity if they wanted to ramp up significantly.