it doesnt matter how many people are making the blockchain, every 10 minutes (on average) a new block is created. This system is self-regulating, so if there are more miners, the problems become harder to solve, so that they will still be solved in 10 minutes (but this increases the security), but if there are less miners the problems become easier, so they still take 10 minutes to solve (but the network gets less secure).

Right now, every 10 minutes, 25 new bitcoins are created (and we already have 14,800,000 bitcoins). In a year a total of 1.314.000 bitcoins will be generated, so that's about 10% of what we have, which means that in theory the inflation would be 10% (in practice the bitcoin value still can go up because more people start using it).

But next year, only 12.5 bitcoin will be made every 10 minutes (so 75 per hour instead of 150 per hour). Which means that only about 650.000 new bitcoins will be made per year, which is less than 5% inflation.

It's still quite a lot, but every 4 years or so this will keep on halving. Until almost no new bitcoins will be created. (In 2140 or so, no new bitcoins will be created at all).