Err, you realise it has a large global presence, yes? If not the largest of the Protestant groups?
As a matter of fact, no, I did not know that.
But ultimately, that is unimportant, unremarkable even. Protestantism is divided among so many different denominations (and keeps splitting further) that it is a major challenge to even count them. There are no clear best criteria, and there is not a lot of benefit in pursuing those criteria.
In practice, the various denominations and branches are significant mostly at the political level, and in proportions that have more to do with their visibility than their numbers.
Here in Brazil, at least, traditional Protestant churches are very much present... but they are definitely less influential than the most flamboyant Neo-charismatic churches such as the Assemblies of God and UCKG. Both traditional and Neo-charismatic Protestantism are divided in myriad denominations, and there just isn't much growth in the most traditional ones. Nor are Brazilians - Christian or otherwise - all that aware of what the divisions and differences even are. For instance, there are plenty of Presbiterian and Baptist Churches - and they are all over the place far as their expectations go. Some are very strict, some very liberal. Some very flamboyant and backwards, some very discreet and sober. It is all determined on a case-by-case basis.
Christians here tend to care about who their local preachers and what they have to say, more than about actual doctrine. To an extent that is true even of the Roman Catholic Church.